Method of and apparatus for transmitting data

ABSTRACT

A method of transmitting data by which cipher-transmission of digital information data for which forbidden codes including timing identification codes are predetermined can be carried out with enciphered digital information data without containing undesirable forbidden code, in which digital information data contained in word sequence data which contain also time reference code data composed of the timing identification codes are subjected to enciphering process without producing the forbidden code to produce the enciphered digital information data which do not contain any forbidden code and then enciphered word sequence data are constituted with the enciphered digital information data and the time reference code data to be transmitted.

This is a continuation of application Ser. No. 10/483,376, filed Jan. 9,2004 now U.S. Pat. No. 7,965,840, which is based on InternationalApplication PCT/JP03/05676 filed May 7, 2003, pursuant to 35 USC 371,and is entitled to the priority filing date of Japanese applications2002-135039, filed on May 10, 2002, the entirety of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a method of transmitting data by whichdigital information data or multiple data obtained by adding digitalancillary data to the digital information data are subjected toenciphering process and enciphered data obtained thereby are transmittedso that original data can be reproduced by subjecting the enciphereddata to deciphering process, or an apparatus for transmitting data onwhich the method of transmitting data mentioned above is performed.

TECHNICAL BACKGROUND

In the field of data transmission by which digital data representingvarious kinds of signal information are transmitted, there have beenproposed to subject digital data which are to be transmitted toenciphering process at a transmission side and to reproduce originaldata by subjecting the enciphered digital data to deciphering process ata receiving side, in order to prevent the digital data from beingeavesdropped on a data transmission line. One of typical algorisms forenciphering digital data is the DES (Date Encryption Standard) publishedin 1977 by the National Bureau of Standards, the United State ofAmerica.

With cipher-transmission based on the DES, digital data are encipheredin accordance with the rules determined by enciphering key data preparedpreviously to produce enciphered digital data and the enciphered digitaldata are deciphered in accordance with the rules determined bydeciphering key data prepared previously to reproduce original digitaldata. The deciphering key data are prepared to be the same as theenciphering key data so that each of the deciphering key data and theenciphering key data are formed with common data. The algorisms forenciphering and deciphering have been opened to the public and thecommon key data are kept secret for the purpose of enciphering.

FIG. 1 shows a basic structure of a cipher-transmission system accordingto the DES. In the basic structure shown in FIG. 1, digital data to betransmitted are supplied to a DES enciphering portion 11 as originaldata. Enciphering key data prepared previously are also supplied to theDES enciphering portion 11. In the DES enciphering portion 11, theoriginal data are subjected to the DES enciphering process in accordancewith the rules determined by the enciphering key data to produceenciphered data. The enciphered data obtained from the DES encipheringportion 11 are transmitted through a data transmission line 12 havingone end thereof connected with the DES enciphering portion 11.

The enciphered data having been transmitted through the datatransmission line 12 are supplied to a DES deciphering portion 13 withwhich the other end of the data transmission line 12 is connected.Deciphering key data which is the same as the enciphering key data arealso supplied to the DES deciphering portion 13. In the DES decipheringportion 13, the enciphered data are subjected to the DES decipheringprocess in accordance with the rules determined by the deciphering keydata to reproduce the original data.

In the field of video signals, digitalization of video signals has beenaimed for actualizing diversification in information to be transmitted,improvements in quality of images reproduced from the video signal andso on. For example, there has been proposed the High DefinitionTelevision (HDTV) system which uses a digital video signal composed ofdigital word sequence data representing video signal information. Thedigital video signal under the HDTV system (hereinafter, referred to theHD signal) is formed in accordance with, for example, the BTA S-002which is one of a series of standards established by the BroadcastingTechnology Association (BTA) in Japan so as to be in the form of Y andP_(B)/P_(R) signals or G, B and R signals.

In the case of the Y and P_(B)/P_(R) signals, Y represents a luminancesignal and P_(B)/P_(R) represent color difference signals. In the caseof the G, B and R signals, G, B and R represent green, blue and redprimary color signals, respectively.

The HD signal is a digital television signal by which each frame pictureis formed with first and second field pictures each appearing at a rateof 60 Hz and which is constituted in accordance with an arrangementsincluding a frame rate of 30 Hz, 1125 lines per frame, 2,200 datasamples per line and a sampling frequency of 74.25 MHz. For example, theHD signal in the form of Y and P_(B)/P_(R) signals is constituted inaccordance with such data formats as shown in FIGS. 2A and 2B.

The data formats shown in FIGS. 2A and 2B include a part of a portioncorresponding to, a line period (hereinafter, referred to a line periodportion) of a luminance signal data sequence (hereinafter, referred to aY data sequence) as shown in FIG. 2A, which represents a luminancesignal component of a video signal, and a part of a line period portionof a color difference signal data sequence (hereinafter, referred aP_(B)/P_(R) data sequence) as shown in FIG. 2B, which represents colordifference signal components of the video signal. Each of data wordsconstituting the Y data sequence or the P_(B)/P_(R) data sequence iscomposed of 10 bits. This means that each of the Y data sequence and theP_(B)/P_(R) data sequence constitutes 10-bit word sequence data having aword transmission rate of, for example, 74.25 Mwps.

In the Y data sequence, each line period portion of which is formed witha portion corresponding to a horizontal blanking period and a portioncorresponding to a video data period appearing after the horizontalblanking period, time reference code data SAV (Start of Active Video)which are composed of four 10-bit words (3FF(Y), 000(Y), 000(Y), XYZ(Y):3FF and 000 are hexadecimal numbers and (Y) indicates a word containedin the Y data sequence) are provided just before the portioncorresponding to the video data period and another time reference codedata EAV (End of Active Video) which are composed of four 10-bit words(3FF(Y), 000(Y), 000(Y), XYZ(Y)) are provided just after the portioncorresponding to the video data period. Similarly, in the P_(R)/P_(R)data sequence, each line period portion of which is formed with aportion corresponding to a horizontal blanking period and a portioncorresponding to a video data period appearing after the horizontalblanking period, time reference code data SAV which are composed of four10-bit words (3FF(C), 000(C), 000(C), XYZ(C):(C) indicates a wordcontained in the P_(R)/P_(R) data sequence) are provided just before theportion corresponding to the video data period and another timereference code data EAV which are composed of four 10-bit words (3FF(C),000(C), 000(C), XYZ(C)) are provided just after the portioncorresponding to the video data period. The time reference code data EAVand SAV contained in the Y data sequence are provided in the portioncorresponding to the horizontal blanking period of the Y data sequenceand the time reference code data EAV and SAV contained in theP_(R)/P_(R) data sequence are provided in the portion corresponding tothe horizontal blanking period of the P_(B)/P_(R) data sequence.

Initial three 10-bit words (3FF, 000, 000) of four 10-bit words (3FF,000,000, XYA), each of which is shown with (Y) or (C), are used forestablishing word synchronization or line synchronization and a last one10-bit word (XYZ) of four 10-bit words (3FF, 000, 000, XYA), which isalso shown with (Y) or (C), is used for discriminating the first fieldfrom the second field in each frame or for discriminating the timereference code data EAV from the time reference code data SAV.

For the HD signal constituted with the Y data sequence and theP_(B)/P_(R) data sequence as described above, some forbidden codes, eachof which can not be used as an information code forming video data orancillary data, and which include timing discrimination codes formingthe time reference code data SAV or EAV, are predetermined. When each ofthe Y data sequence and the P_(B)/P_(R) data sequence constitutes 10-bitword sequence data, the forbidden codes mentioned above are 000h to 003hand 3FCh to 3FFh (000 to 003 and 3FC to 3FF are hexadecimal numbers andh indicates a hexadecimal number), that is, 0000000000 to 0000000011 and1111111100 to 1111111111, as shown in FIG. 3.

When the HD signal constituted with the Y data sequence and theP_(B)/P_(R) data sequence is subjected to transmission through a datatransmission line, it is desired for the HD signal to be converted toserial data from word sequence data so as to be subjected to serialtransmission through a simplified data transmission line. In connectionwith the serial transmission of the HD signal constituted with the Ydata sequence and the P_(B)/P_(R) data sequence, it has beenstandardized to transmit the HD signal in conformity with the HD. SDI(High Definition Serial Digital Interface) according to the BTA S-004which is one of a series of standards established by the BTA in Japan.

In the transmission of the HD signal in conformity with the HD SDI, theY data sequence and the P_(B)/P_(a) data sequence are multiplexed, withtheir portions corresponding to the horizontal blanking periods in eachof which the time reference code data EAV and SAV are provided and whichsynchronize with each other, to produce a multiple word sequence asshown in FIG. 4 and then the multiple word sequence is converted toserial data to be transmitted. Each of data words constituting themultiple word sequence shown in FIG. 4 is composed of 10 bits and theword transmission rate of the multiple word sequence shown in FIG. 4 isset to be 74.25 Mwps×2=148.5 Mwps. In the multiple word sequence thusobtained as shown in FIG. 4, multiple time reference code data (multipleSAV) which are composed of eight 10-bit words (3FF(C), 3FF(Y), 000(C),000(Y), 000(C), 000(Y), XYZ(C), XYZ (Y)) are provided just before theportion corresponding to a video data period and another multiple timereference code data EAV (multiple EAV) which are composed of eight10-bit words (3FF(C), 3FF(Y), 000(C), 000(Y), 000(C), 000(Y), XYZ(C),XYZ(Y)) are provided just after the portion corresponding to the videodata period.

The each of the 10-bit words constituting the multiple word sequence issent bit by bit from the least significant bit (LSB) to the mostsignificant bit (MSB) so that the multiple word sequence is converted toa serial data. Then, the serial data is subjected to scrambling processto produce a serial transmission HD signal (hereinafter, referred to anHD-SDI signal) and the HD-SDI signal is transmitted through a datatransmission line. The HD-SDI signal thus transmitted has a bittransmission rate of, for example, 148.5 Mwps×10=1.485 Gbps.

In the case of the transmission of the HD-SDI signal through the datatransmission line, it is also desired to subject the HD-SDI signal toenciphering process at a transmission side and to reproduce originalHD-SDI data by subjecting the enciphered HD-SDI data to decipheringprocess at a receiving side, in order to prevent the HD-SDI data frombeing eavesdropped on the data transmission line. Suchcipher-transmission of the HD-SDI signal can be theoretically carriedout with a cipher-transmission system which is similar to thecipher-transmission system according to the DES having the basicstructure shown in FIG. 1.

For example, when an HD signal is converted to an HD-SDI signal inaccordance with the HD SDI to be transmitted through a data transmissionline and the transmitted HD-SDI signal is reconverted to the HD signalin accordance with the HD SDI to be supplied to, for example, a videoprojector which operates to display images based on the HD signal, it isconsidered to have such a cipher-transmission system as shown in FIG. 5for conducting the cipher-transmission of the HD-SDI signal.

In the cipher-transmission system shown in FIG. 5, an HD-SDI signal DHSderived from an HD-SDI signal generating portion 15, in which an HDsignal obtained from a video camera or the like is converted to theHD-SDI signal HDS in accordance with the HD SDI, is supplied to anHD-SDI enciphering portion 16. Enciphering key data DDK preparedpreviously are also supplied to the HD-SDI enciphering portion 16. Inthe HD-SDI enciphering portion 16, the HD-SDI signal DHS is firstsubjected to serial to parallel (S/P) conversion to reproduce theoriginal HD signal constituted with Y and P_(B)/P_(R) data sequences anda video data portion of the reproduced HD signal is subjected to the DESenciphering process in accordance with the rules determined by theenciphering key data DDK to produce an enciphered HD signal. Then, inthe HD-SDI enciphering portion 16, the enciphered HD signal is subjectedto parallel to serial (P/S) conversion to produce enciphered serial dataDHSE. The enciphered serial data DHSE are derived from the HD-SDIenciphering portion 16 to be transmitted through a data transmissionline 17 having one end thereof connected with the HD-SDI encipheringportion 16.

The enciphered serial data DHSE having been transmitted through the datatransmission line 17 are supplied to an HD-SDI deciphering portion 18with which the other end of the data transmission line 17 is connected.Deciphering key data DDK which is the same as the enciphering key dataDDK supplied to the HD-SDI enciphering portion 16 are also supplied tothe HD-SDI deciphering portion 18. In the HD-SDI deciphering portion 18,the enciphered serial data DHSE are subjected to the S/P conversion toreproduce the enciphered HD signal and a video data portion of theenciphered HD signal is subjected to the DES deciphering process inaccordance with the rules determined by the deciphering key data DDK toreproduce the original HD signal constituted with Y and P_(B)/P_(R) datasequences. Then, in the HD-SDI deciphering portion 18, the Y andP_(B)/P_(R) data sequences constituting the reproduced HD signal aremultiplexed with each other in accordance with the HD SDI to produce aword multiple data sequence and the word multiple data sequence thusobtained are subjected to the P/S conversion to reproduce the HD-SDIsignal DHS.

The HD-SDI signal DHS obtained from the HD-SDI deciphering portion 18 issupplied to a video projector 19. In the video projector 19, the HDsignal is reproduced from the HD-SDI signal DHS and used for display ofimages.

In such a manner as described above, the cipher-transmission of theHD-SDI signal is seemingly carried out. However, in thecipher-transmission system shown in FIG. 5, a serious problem, withwhich the deciphering process to which the enciphered serial data DHSEare subjected in the HD-SDI deciphering Portion 18 is interfered and thereproduction of the HD signal from the HD-SDI signal DHI can not beappropriately carried out in the video projector 19, is brought about.

This problem is explained as follows.

When the HD-SDI signal DHS is converted to the HD signal and the videosignal portion of the HD signal is subjected to the DES encipheringprocess in accordance with the rules determined by the enciphering keydata DDK to produce the enciphered HD signal in the HD-SDI encipheringportion 16, the bidden codes aforementioned, that is, 000h to 003h and3FCh to 3FFh are undesirably contained with a certain probability in thevideo data portion of the enciphered HD signal though the video dataportion of the HD signal does not contain anyone of the forbidden codesof 000h to 003h and 3FCh to 3FFh. As a result, the enciphered serialdata DHSE are produced based on the enciphered HD signal which has thevideo data portion containing the forbidden codes in the HD-SDIenciphering portion 16 and then transmitted from the HD-SDI encipheringportion 16 through the data transmission line 17 to the HD-SDIdeciphering portion 18.

The forbidden codes are originally contained in the HD signal in theform of the timing identification codes constituting the time referencecodes SAV and EAV and portions of the HD-SDI signal DHS whichcorresponds to the serial data converted from the forbidden codesconstituting the time reference codes data SAV and EAV are detected tobe used for making word-synchronization between the HD-SDI signal DHSand the reproduced HD signal so that the reproduced HD signal isproperly obtained when the original HD signal is reproduced from theHD-SDI signal DHS.

Under such a situation, when the enciphered serial data DHSE which areproduced based on the enciphered HD signal having the video data portioncontaining the forbidden codes is transmitted from the HD-SDIenciphering portion 16 through the data transmission line 17 to theHD-SDI deciphering portion 18, it is feared in the HD-SDI decipheringportion 18 that a portion of the enciphered serial data DHSE whichcorresponds to the serial data converted from the forbidden codescontained in video data portion of the enciphered HD signal isundesirably detected, in addition to portions of the enciphered serialdata DHSE which properly correspond to the serial data converted fromthe forbidden codes contained in the HD signal for constituting the timereference codes SAV and EAV, just as a portion of the enciphered serialdata DHSE which corresponds to the serial data converted from theforbidden codes constituting the time reference codes data SAV or EAV.If the portion of the enciphered serial data DHSE which corresponds tothe serial data converted from the forbidden codes contained in videodata portion of the enciphered HD signal is also detected just as theportion of the enciphered serial data DHSE which corresponds to theserial data converted from the forbidden codes constituting the timereference codes data SAV or EAV when the ciphered HD signal isreproduced from the enciphered serial data DHSE in the HD-SDIdeciphering portion 18, appropriate word-synchronization between theenciphered serial data DHSE and the ciphered HD signal to be reproducedis not made and therefore the ciphered HD signal can not be properlyreproduced.

Further, as a result, the HD-SDI signal DHS which is obtained from theHD-SDI deciphering portion 18 to be supplied to the video projector 19comes to have improper contents and accordingly the HD signal which isreproduced from the HD-SDI signal DHS from the HD-SDI decipheringportion 18 in the video projector 19 also comes to have improper videodata.

The problems mentioned above are brought about by the data transmissionin which the forbidden codes are undesirably contained with a certainprobability in the video data portion of the enciphered HD signal andthereby the ciphered serial data DHSE contain an undesirable portionthereof corresponding to the serial data converted from the forbiddencodes when the HD-SDI signal DHS is reconverted to the HD signal to besubjected to the DES enciphering process in accordance with the rulesdetermined by the deciphering key data DDK to produce the ciphered HDsignal and the ciphered serial data DHSE are obtained based on theciphered HD signal to be transmitted in the HD-SDI enciphering portion16.

Accordingly, it is an object of the present invention to provide a firstmethod of transmitting data which can be applicable to enciphered datatransmission in which digital information data which correspond toserial data obtained based on word sequence data which contain digitalinformation data in which forbidden codes including timingidentification codes are contained and time reference code dataconstituted with the timing identification codes, for example, such dataas constituting an HD-SDI signal, are subjected to enciphering processto produce enciphered serial data and the enciphered serial data aretransmitted, and by which the ciphered data transmission is carried outunder a condition wherein the enciphered serial data can be preventedfrom containing an undesirable portion thereof corresponding to serialdata converted from the forbidden codes.

Another object of the present invention is to provide a first apparatusfor transmitting data in which the first method of transmitting datamentioned above is carried out.

A further object of the present invention is to provide a second methodof transmitting data which can be applicable to enciphered datatransmission in which digital information data which correspond toserial data obtained based on word sequence data which contain digitalinformation data in which forbidden codes including timingidentification codes are contained and time reference code dataconstituted with the timing identification codes, for example, such dataas constituting an HD-SDI signal, are subjected to enciphering processto produce enciphered serial data and the enciphered serial data aretransmitted, and by which the ciphered data transmission is carried outunder a condition wherein the enciphered serial data can be preventedfrom containing an undesirable portion thereof corresponding to serialdata converted from the forbidden codes and the original digitalinformation data can be surely reproduced by subjecting enciphereddigital information data obtained based on the transmitted encipheredserial data to deciphering process.

A still further object of the present invention is to provide a secondapparatus for transmitting data in which the second method oftransmitting data mentioned above is carried out.

DISCLOSURE OF THE INVENTION

According to the invention there is provided a method of transmittingdata, which comprises the steps of subjecting digital information datato enciphering process in such a manner as not to produce forbidden codefor producing enciphered digital information data which do not containany forbidden code, said digital information data containing a group ofdata including timing identification data in the form of forbidden codeswhich are not used as information codes for representing information andcontained in word sequence data which contain also time reference codedata constituted with the timing identification codes in addition to thedigital information data, producing enciphered word sequence data whichinclude the enciphered digital information data and the time referencecode data, and transmitting the enciphered word sequence data.

According to the invention there is provided an apparatus fortransmitting data, which comprises an enciphering processor forsubjecting digital information data to enciphering process in such amanner as not to produce forbidden code for producing enciphered digitalinformation data which do not contain any forbidden code, said digitalinformation data containing a group of data including timingidentification data in the form of forbidden codes which are not used asinformation codes for representing information and contained in wordsequence data which contain also time reference code data constitutedwith the timing identification code in addition to the digitalinformation data, a data multiplexer for multiplexing the enciphereddigital information data obtained from the enciphering processor and thetime reference code data with each other to produce enciphered wordsequence data, and a data transmitting portion for transmitting theenciphered word sequence data obtained from the data multiplexer.

According to the invention claimed, there is provided a method oftransmitting data, which comprises the steps of subjecting digitalinformation data to enciphering process in such a manner as not toproduce forbidden code for producing enciphered digital information datawhich do not contain any forbidden code, said digital information datacontaining a group of data including timing identification data in theform of forbidden codes which are not used as information codes forrepresenting information and contained in word sequence data whichcontain also time reference code data constituted with the timingidentification codes in addition to the digital information data,producing enciphered word sequence data which include the enciphereddigital information data and the time reference code data, transmittingthe enciphered word sequence data, receiving the enciphered wordsequence data transmitted for obtaining the enciphered digitalinformation data from the enciphered word sequence data, causing theenciphered digital information data to be subjected to decipheringprocess for reproducing the digital information data, and reproducingthe word sequence data which include the reproduced digital informationdata and the time reference code data.

According to the invention there is provided an apparatus fortransmitting data, which comprises an enciphering processor forsubjecting digital information data to enciphering process in such amanner as not to produce forbidden code for producing enciphered digitalinformation data which do not contain any forbidden code, said digitalinformation data containing a group of data including timingidentification data in the form of forbidden codes which are not used asinformation codes for representing information and contained in wordsequence data which contain also time reference code data constitutedwith the timing identification code in addition to the digitalinformation data, a first data multiplexer for multiplexing theenciphered digital information data obtained from the encipheringprocessor and the time reference code data with each other to produceenciphered word sequence data, a data transmitting portion fortransmitting the enciphered word sequence data obtained from the firstdata multiplexer, a deciphering processor for receiving the encipheredword sequence data transmitted by the data transmitter to obtain theenciphered digital information data from the enciphered word sequencedata and causing the enciphered digital information data to be subjectedto deciphering process for reproducing the digital information data, anda second data multiplexer for multiplexing the reproduced digitalinformation data and the time reference code data with each other toreproduce the word sequence data.

In the method of transmitting data the digital information datacontained in the word sequence data which contain also the timereference code data constituted with the timing identification codes inaddition to the digital information data are subjected to theenciphering process in such a manner as not to produce forbidden codefor producing the enciphered digital information data which do notcontain any forbidden code, and the enciphered digital information dataand the time reference code data are multiplexed with each other toproduce the enciphered word sequence data to be transmitted.

As described above, since the enciphered digital information data whichdo not contain any forbidden code are produced and the enciphered wordsequence data containing the enciphered digital information data and thetime reference code data are subjected to conversion to the encipheredserial data to be transmitted, the enciphered serial data which do nothave an undesirable portion thereof corresponding to serial dataconverted from the forbidden codes are obtained when the enciphered wordsequence data are converted to the enciphered serial data the encipheredserial data.

Accordingly, when the method of transmitting data is applied to theenciphered data transmission in which the digital information data whichcorrespond to the serial data obtained based on the word sequence datawhich contain the digital information data in which the forbidden codesincluding the timing identification codes are contained and the timereference code data constituted with the timing identification codes,for example, such data as constituting the HD-SDI signal, are subjectedto the enciphering process to produce the enciphered serial data and theenciphered serial data are transmitted, the enciphered data transmissionis carried out under the condition wherein the enciphered serial datacan be prevented from containing the undesirable portion thereofcorresponding to the serial data converted from the forbidden codes.

Further, in the method of transmitting data the digital information datacontained in the word sequence data which contain also the timereference code data constituted with the timing identification codes inaddition to the digital information data are subjected to theenciphering process in such a manner as not to produce forbidden codefor producing the enciphered digital information data which do notcontain any forbidden code, the enciphered digital information data andthe time reference code data are multiplexed with each other to producethe enciphered word sequence data to be transmitted, and the enciphereddigital information data obtained from the enciphered word sequence dataare subjected to the deciphering process for reproducing the digitalinformation data to be multiplexed with the time reference code data toreproduce the word sequence data.

As described above, since the enciphered digital information data whichdo not contain any forbidden code are produced and the enciphered wordsequence data containing the enciphered digital information data and thetime reference code data are subjected to conversion to the encipheredserial data to be transmitted, the enciphered serial data which do nothave an undesirable portion thereof corresponding to serial dataconverted from the forbidden codes are obtained when the enciphered wordsequence data are converted to the enciphered serial data and theoriginal serial data are properly reproduced from the transmittedenciphered serial data when the transmitted enciphered serial data aresubjected to the deciphering process. Then, the word sequence data aresurely reproduced based on the enciphered word sequence data bysubjecting the enciphered digital information data obtained from theenciphered word sequence data to various data processes including thedeciphering process.

Accordingly, when the method of transmitting data is applied to theenciphered data transmission in which the digital information data whichcorrespond to the serial data obtained based on the word sequence datawhich contain the digital information data in which the forbidden codesincluding the timing identification codes are contained and the timereference code data constituted with the timing identification codes,for example, such data as constituting the HD-SDI signal, are subjectedto the enciphering process to produce the enciphered serial data to betransmitted, and the original serial data are reproduced from thetransmitted enciphered serial data, the enciphered data transmission iscarried out under the condition wherein the enciphered serial data canbe prevented from containing the undesirable portion thereofcorresponding to the serial data converted from the forbidden codes andthe original serial data can be surely reproduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a basic structure of acipher-transmission system according to the DES;

FIGS. 2A and 2B are illustrations used for explaining an example of dataformat of an HD signal;

FIG. 3 is a table showing forbidden codes contained in the HD signalhaving the data format shown in FIGS. 2A and 2B;

FIG. 4 is an illustration used for explaining another example of dataformat of an HD signal;

FIG. 5 is a schematic block diagram showing a cipher-transmission systemapplicable to the cipher-transmission of an HD-SDI signal;

FIG. 6 is a block diagram showing an embodiment of apparatus fortransmitting data;

FIG. 7 is a schematic block diagram showing an embodied structure of anenciphering portion in the embodiment of apparatus for transmitting datashown in FIG. 6;

FIG. 8 is a schematic block diagram showing a first embodied structureof a Y data enciphering portion in the embodied structure shown in FIG.7;

FIG. 9 is a schematic block diagram showing a first embodied structureof a C data enciphering portion in the embodied structure shown in FIG.7;

FIG. 10 is an illustration used for explaining data writing in and datareading from a memory shown in each of FIGS. 8 and 9;

FIG. 11 is a schematic block diagram showing a second embodied structureof the Y data enciphering portion in the embodied structure shown inFIG. 7;

FIG. 12 is a schematic block diagram showing a second embodied structureof the C data enciphering portion in the embodied structure shown inFIG. 7;

FIG. 13 is an illustration used for explaining the operation of anadding-subtracting modulo operation unit shown in each of FIG. 11 andFIG. 12;

FIG. 14 is a schematic block diagram showing a third embodied Structureof the Y data enciphering portion in the embodied structure shown inFIG. 7;

FIG. 15 is a schematic block diagram showing a third embodied structureof the C data enciphering portion in the embodied structure shown inFIG. 7;

FIG. 16 is an illustration used for explaining data writing in and datareading from a memory shown in each of FIGS. 14 and 15;

FIG. 17 is a schematic block diagram showing an example of a randomnumber generating portion which can be used in place of a random numbergenerating portion shown in each of FIGS. 8 and 9, FIGS. 11 and 12 andFIGS. 14 and 15;

FIG. 18 is a schematic block diagram showing a fourth embodied structureof the Y data enciphering portion in the embodied structure shown inFIG. 7;

FIG. 19 is a schematic block diagram showing a fourth embodied structureof the C data enciphering portion in the embodied structure shown inFIG. 7;

FIG. 20 is a schematic block diagram showing a fifth embodied structureof the Y data enciphering portion in the embodied structure shown inFIG. 7;

FIG. 21 is a schematic block diagram showing a fifth embodied structureof the C data enciphering portion in the embodied structure shown inFIG. 7;

FIG. 22 is a schematic block diagram showing an example of a randomnumber generating portion which can be used in place of a random numbergenerating portion shown in each of FIGS. 18 to 21;

FIG. 23 is a block diagram showing, under a condition combined with theembodiment of apparatus for transmitting data shown in FIG. 6;

FIG. 24 is a schematic block diagram showing an embodied structure of adeciphering portion in the embodiment of apparatus for transmitting datashown in FIG. 23;

FIG. 25 is a schematic block diagram showing a first embodied structureof a Y data deciphering portion in the embodied structure shown in FIG.24;

FIG. 26 is a schematic block diagram showing a first embodied structureof a C data deciphering portion in the embodied structure shown in FIG.24;

FIG. 27 is a schematic block diagram showing a second embodied structureof the Y data deciphering portion in the embodied structure shown inFIG. 24;

FIG. 28 is a schematic block diagram showing a second embodied structureof the C data deciphering portion in the embodied structure shown inFIG. 24;

FIG. 29 is a schematic block diagram showing a third embodied structureof the Y data deciphering portion in the embodied structure shown inFIG. 24;

FIG. 30 is a schematic block diagram showing a third embodied structureof the C data deciphering portion in the embodied structure shown inFIG. 24;

FIG. 31 is a schematic block diagram showing an example of a randomnumber generating portion which can be used in place of a random numbergenerating portion shown in each of FIGS. 25 to 30;

FIG. 32 is a schematic block diagram showing a fourth embodied structureof the Y data deciphering portion in the embodied structure shown inFIG. 24;

FIG. 33 is a schematic block diagram showing a fourth embodied structureof the C data deciphering portion in the embodied structure shown inFIG. 24;

FIG. 34 is a schematic block diagram showing a fifth embodied structureof the Y data deciphering portion in the embodied structure shown inFIG. 24;

FIG. 35 is a schematic block diagram showing a fifth embodied structureof the C data deciphering portion in the embodied structure shown inFIG. 24; and

FIG. 36 is a schematic block diagram showing an example of a randomnumber generating portion which can be used in place of a random numbergenerating portion shown in each of FIGS. 32 to 35.

EMBODIMENTS MOST PREFERABLE FOR WORKING OF THE INVENTION

Fig. shows an embodiment of apparatus for transmitting data according tothe invention claimed in claim 9 or claim 10 of the present application,in which an embodiment of method of transmitting data according to theinvention claimed in claim 1 or claim 2 of the present application iscarried out

Referring to FIG. 6, an HD-SDI signal DHS derived from an HD-SDI signalgenerating portion 21 is supplied to a parallel data producing portion22. The HD-SDI signal DHS is generated by subjecting word sequence databased on an HD signal which contains Y and P_(B)/P_(R) data sequenceseach constituting 10-bit word sequence data, as shown in FIG. 2, to P/Sconversion. The word sequence data based on the HD signal are producedby causing the Y and P_(B)/P_(R) data sequences contained in the HDsignal to be multiplexed with each other in conformity with the HD SDI.

Each of the Y and P_(B) data sequences constituting the HD signalcontains time reference code data SAV and EAV each constituted withtiming identification codes 3FFh and 000h. A video data portion of eachof the Y and P_(B)/P_(R) data sequences is so constituted as not tocontain anyone of forbidden codes which are eight code of 000h to 003hand 3FCh to 3FFh including the timing identification codes 3FFh and000h, as shown in FIG. 3, and not used as information codes forrepresenting information. Consequently, the HD-SDI signal DHS containsthe forbidden codes in the form of serial data converted from threetiming identification codes arranged in order of 3FFh, 000h and 000h soas to constitute the time reference code data SAV or EAV.

In the parallel data producing portion 22, the HD-SDI signal DHS aresubjected to level equalization for compensating for reduction in highfrequency components caused on a data transmission line to produce anequalized HD-SDI signal DHS′ in an equalizer 23. The equalized HD-SDIsignal DHS′ obtained from the equalizer 23 is supplied to both of anNRZI converter 24 and a clock reproducing portion 25. In the clockreproducing portion 25, a clock signal CK contained in the equalizedHD-SDI signal DHS′ is reproduced.

The clock signal CK obtained from the clock reproducing portion 25 issupplied to the NRZI converter 24 so that NRZI (Non-return to ZeroInverted) conversion of the equalized HD-SDI signal DHS′ is carried outwith the clock signal CK in the NRZI converter 24. Therefore, an HD-SDIsignal DHSC which has been subjected to the NRZI conversion is derivedto be supplied to a descrambling portion 26. The clock signal CKobtained from the clock reproducing portion 25 is also supplied to thedescrambling portion 26. In the descrambling portion 26, the HD-SDIsignal DHSC is descrambled to produce a descrambled HD-SDI signal DHSD.The descrambled HD-SDI signal DHSD is derived from the descramblingportion 26 is supplied to both of an S/P converter 27 and a wordsynchronous signal generating portion 28.

The clock signal CK obtained from the clock reproducing portion 25 isalso supplied to the word synchronous signal generating portion 28. Aportion of the descrambled HD-SDI signal DHSD, which corresponds toserial data converted from the timing identification codes arranged inorder of 3FFh, 000h, 000h for constituting the time reference code dataSAV or EAV, is detected with the clock signal CK and a word synchronoussignal SWS is produced in response to the detection of theaforementioned portion, in the word synchronous signal generatingportion 28. The word synchronous signal SWS obtained from the wordsynchronous signal generating portion 28 is supplied to the S/Pconverter 27. The clock signal CK obtained from the clock reproducingportion 25 is also supplied to the S/P converter 27 and the descrambledHD-SDI signal. DHSD is subjected to S/P conversion under the conditionof word-synchronization according to the word synchronous signal SWS inthe S/P converter 27. With the S/P conversion thus processed, thedescrambled HD-SDI signal DHSD is converted into 20-bit word sequencedata DHP which are constituted with the Y and P_(B)/P_(R) data sequenceseach forming 10-bit word sequence data and multiplexed bit by bit withtheir time reference code data SAV and EAV synchronizing with eachother.

The 20-bit word sequence data DHP obtained from the S/P converter 27 aresupplied to a data dividing portion 29. In the data dividing portion 29,the 20-bit word sequence data DHP are divided into multiple timereference data DAV, multiple ancillary data DAA and multiple video dataDVI. The multiple time reference data DAV are obtained in the form of20-bit word sequence data constituted with the time reference code dataSAV and EAV, line number data, error detection code data and so on inthe Y data sequence in the form of 10-bit word sequence data and thetime reference code data SAV and EAV, line number data, error detectioncode data and so on in the P_(B)/P_(R) data sequence in the form of10-bit word sequence data which are multiplexed bit by bit under thecondition of word-synchronization. The multiple ancillary data DAA areobtained in the form of 20-bit word sequence data constituted with theancillary data in the Y data sequence in the form of 10-bit wordsequence data and the ancillary data in the P_(B)/P_(R) data sequence inthe form of 10-bit word sequence data which are multiplexed bit by bitunder the condition of word-synchronization. The multiple video data DVIare obtained in the form of 20-bit word sequence data containing Ysignal video data DVY constituting the video data portion in the Y datasequence in the form of 10-bit word sequence data and C signal videodata DVC constituting the video data portion in the P_(B)/P_(R) datasequence in the form of 10-bit word sequence data which are multiplexedbit by bit under the condition of word-synchronization.

The multiple time reference data DAV, the multiple ancillary data DAAand the multiple video data DVI obtained from the data dividing portion29 are sent from the parallel data producing portion 22 to anenciphering processor 30. The enciphering processor 30 is constitutedwith an enciphering portion 31 and a key data generating portion 32.

The multiple time reference data DAV and the multiple ancillary data DAApass through the enciphering processor 30 to be supplied to a serialdata producing portion 33. The multiple video data DVI are supplied tothe enciphering portion 31 in the enciphering processor 30. The key datagenerating portion 32 is operative to supply the enciphering portion 31with predetermined key data DEY.

In the enciphering portion 31, the multiple video data DVI in the formof 20-bit word sequence data are subjected to, for example, the DESenciphering process in accordance with the rules determined by the keydata DEY to produce enciphered video data DXI in the form of 20-bit wordsequence data

FIG. 7 shows an embodied structure of the enciphering portion 31.

In the embodied structure shown in FIG. 7, the multiple video data DVIin the form of 20-bit word sequence data are supplied to a bit dividingportion 40. In the bit dividing portion 40, the multiple video data DVIare divided into the Y signal video data DVY in the form of 10-bit wordsequence data and the signal video data DVC in the form of 10-bit wordsequence data, which are separately sent from the bit dividing portion40.

The Y signal video data DVY and the C signal video data DVC obtainedfrom the bit dividing portion 40 are supplied to a Y data encipheringportion 41 and a C data enciphering portion 42, respectively. The keydata DEY obtained from the key data generating portion 32 are alsosupplied to both of the Y data enciphering portion 41 and the C dataenciphering portion 42.

In the Y data enciphering portion 41, the Y signal video data DVY in theform of 10-bit word sequence data are subjected to the DES encipheringprocess in accordance with the rules determined by the key data DEY, toproduce enciphered Y signal video data DXY in the form of 10-bit wordsequence data. In the C data enciphering portion 42, the C signal videodata DVC in the form of 10-bit word sequence data are subjected to theDES enciphering process in accordance with the rules determined by thekey data DEY to produce enciphered C signal video data DXC in the formof 10-bit word sequence data.

The DES enciphering process to which the Y signal video data DVY aresubjected in the Y data enciphering portion 41 is so performed as not toproduce anyone of the forbidden codes 000h to 003h and 3FCh to 3FFh andthereby the enciphered Y signal video data DXY based on the Y signalvideo data DVY are obtained in the form of 10-bit word sequence datawhich do not contain the forbidden codes 000h to 003h and 3FCh to 3FFh.Similarly, the DES enciphering process to which the C signal video dataDVC are subjected in the C data enciphering portion 42 is so performedas not to produce anyone of the forbidden codes 000h to 003h and 3FCh to3FFh and thereby the enciphered C signal video data DXC based on the Csignal video data DVC are obtained in the form of 10-bit word sequencedata which do not contain the forbidden codes 000h to 003h and 3FCh to3FFh.

The enciphered Y signal video data DXY in the form of 10-bit wordsequence data and the enciphered C signal video data DXC in the form of10-bit word sequence data thus obtained from the Y data encipheringportion 41 and the C data enciphering portion 42, respectively, aresupplied to a bit multiplexer 43.

In the bit multiplexer 43, the enciphered Y signal video data DXY in theform of 10-bit word sequence data and the enciphered C signal video dataDXC in the form of 10-bit word sequence data are multiplexed with eachother to produce the enciphered video data DXI in the form of 20-bitword sequence data to be sent from the enciphering portion 31 as outputdata. The enciphered video data DX1 in the form of 20-bit word sequencedata thus obtained do not contain the forbidden codes 000h to 003h and3FCh to 3FFh.

The enciphered video data DXI as the output data from the encipheringportion 31 are sent from the enciphering processor 30 to the serial dataproducing portion 33. In the serial data producing portion 33, themultiple time reference data DAV and the multiple ancillary data DAAeach having passed through the enciphering processor 30 and theenciphered video data DXI are supplied to a data multiplexer 45.

In the data multiplexer 45, the enciphered video data DXI, the multipletime reference data DAV and the multiple ancillary data DAA aresubjected to multiplexing process to produce enciphered 20-bit wordsequence data DXP including the enciphered video data DXI, the multipletime reference data DAV and the multiple ancillary data DAA. Theenciphered 20-bit word sequence data DXP thus obtained in the datamultiplexer 45 are supplied to a P/S converter 46.

In the P/S converter 46, the enciphered 20-bit word sequence data DXPare subjected to P/S conversion to produce enciphered serial data DXSDbased on the enciphered 20-bit word sequence data DXP to be supplied toa scrambling portion 47.

In the scrambling portion 47, the enciphered serial data DXSD aresubjected to scrambling process to produce scrambled enciphered serialdata DXSC to be supplied to a NRZI converter 49. In the NRZI converter49, the scrambled enciphered serial data DXSC are subjected to NRZIconversion to produce enciphered HD-SDI signal DXS. The encipheredHD-SDI signal DXS thus obtained in the NRZI converter 49 is transmittedfrom the serial data producing portion 33 through, for example, acoaxial cable forming a data transmission line.

In the serial data producing portion 33, a portion thereof whichincludes the P/S converter 46, the scrambling portion 47 and the NRZIconverter 49 constitutes a data transmitting portion for transmittingthe enciphered 20-bit word sequence data DXP obtained from the datamultiplexer.

FIGS. 8 and 9 show a first embodied structures of the Y data encipheringportion 41 shown in FIG. 7 and a′first embodied structures of the C dataenciphering portion 42 shown in FIG. 7, respectively.

In the case where the enciphering portion 31 shown in FIG. 6 isconstituted with the Y data enciphering portion 41 having the firstembodied structure shown in FIG. 8 and the C data enciphering portion 42having the first embodied structure shown in FIG. 9, the structure ofthe enciphering portion 31 thus constituted corresponds to an embodimentof apparatus for transmitting.

The first embodied structure shown in FIG. 8 of the Y data encipheringportion 41 is constituted with a memory 51 to which the Y signal videodata DVY in the form of 10-bit word sequence data are supplied as firstreading address data and a random number generating portion 52 to whichthe key data DEY are supplied.

In the random number generating portion 52, a register 53 is operativeto put out, in response to input data, register output data DRZ composedof, for example, 128 bits to be supplied to a DES cipher producingportion 54. Initial input data DIT are supplied to the register 53.

The key data DEY are also supplied to the DES cipher producing portion54. In the DES cipher producing portion 54, the register output data DRZare subjected to DES enciphering process in accordance with the rulesdetermined by the key data DEY to produce cipher data DEZ composed of,for example, 128 bits. The cipher data DEZ obtained from the DES cipherproducing portion 54 are supplied to a bit extracting portion 55 and fedback to the register 53 as another input data. The register 53 isoperative first to put out the register output data DRZ in response tothe initial input data DIT and then to put out the register output dataDRZ in response to the cipher data DEZ obtained from the DES cipherproducing portion 54.

The bit extracting portion 55 is operative to extract 10 bits of 128bits forming the cipher data DEZ as pseudo-random number data DXA. Thepseudo-random number data DXA obtained from the bit extracting portion55 are sent from the random number generating portion 52 to be suppliedto the memory 51 as second reading address data.

1016 (10.24−8) 10-bit words having respectively different 10-bit codeswith the exception of the forbidden codes 000h to 003h and 3FCh to 3FFhare stored in the memory 51. The 10-bit code of each of 1016 10-bitwords is in a specific corresponding relation to the 10-bit code of eachof the 10-bit words constituting the Y signal video data DVY which aresupplied to the memory 51 as the first reading address data, and undersuch specific corresponding relation, 1016 10-bit words are read fromthe memory 51 in response to the Y signal video data DVY and thespecific corresponding relation between the 10-bit code of each of 101610-bit words and the 10-bit code of each of the 10-bit wordsconstituting the Y signal video data DVY varies in response to thepseudo-random number data DXA supplied to the memory 51 as the secondreading address data.

For example, if the 10-bit code of each of the 10-bit words constitutingthe Y signal video data DVY is called a video word data code and the10-bit code of each of 1016 10-bit words stored in the memory 51 iscalled a stored word data code, the stored word data code is in such aspecific corresponding relation as shown with arrowheaded lines in FIG.10 to the video word data code, and under such specific correspondingrelation, the 10-bit words each having the stored word data code areread from the memory 51 in accordance with the arrowheaded lines inresponse to the 10-bit words each having the video word data code. Whenthe pseudo-random number data DXA varies, the specific correspondingrelation shown with arrowheaded lines in FIG. 10 varies also in responseto the variation in the pseudo-random number data DXA.

The 10-bit words each having the stored word data code read out from thememory 51 are successively arranged to produce the enciphered Y signalvideo data DXY in the form of 10-bit word sequence data. Accordingly,this results in that the Y signal video data DVY are subjected to codeconversion for obtaining 10-bit code in response to the pseudo-randomnumber data DXA with the exception of the forbidden codes and therebyconverted into the enciphered Y signal video data DXY in the memory 51.As a result, the enciphered Y signal video data DXY do not contain anyforbidden code.

The first embodied structure shown in FIG. 9 of the C data encipheringportion 42 is constituted with a memory 56 to which the C signal videodata DVC in the form of 10-bit word sequence data are supplied as firstreading address data and a random number generating portion 57 to whichthe key data DEY are supplied.

The random number generating portion 57 is constituted in the samemanner as the random number generating portion 52 shown in FIG. 8. Thecircuit blocks in FIG. 9 corresponding to those in FIG. 8 are markedwith the references common to FIG. 8 and further description thereofwill be omitted. Pseudo-random number data DXA obtained from the randomnumber generating portion 57 are supplied to the memory 56 as secondreading address data.

1016 (1024−8) 10-bit words having respectively different 10-bit codeswith the exception of the forbidden codes 000h to 003h and 3FCh to 3FFhare stored also in the memory 56. The 10-bit code of each of 1016 10-bitwords is in a specific corresponding relation to the 10-bit code of eachof the 10-bit words constituting the C signal video data DVC which aresupplied to the memory 56 as the first reading address data, and undersuch specific corresponding relation, 1016 10-bit words are read fromthe memory 56 in response to the C signal video data DVC and thespecific corresponding relation between the 10-bit code of each of 101610-bit words and the 10-bit code of each of the 10-bit wordsconstituting the C signal video data DVC varies in response to thepseudo-random number data DXA supplied to the memory 56 as the secondreading address data.

For example, if the 10-bit code of each of the 10-bit words constitutingthe C signal video data DVC is called a video word data code and the10-bit code of each of 1016 10-bit words stored in the memory 51 iscalled a stored word data code, the stored word data code is in such aspecific corresponding relation as shown with arrowheaded lines in FIG.10 to the video word data code, and under such specific correspondingrelation, the 10-bit words each having the stored word data code areread from the memory 56 in accordance with the arrowheaded lines inresponse to the 10-bit words each having the video word data code. Whenthe pseudo-random number data DXA varies, the specific correspondingrelation shown with arrowheaded lines in FIG. 10 varies also in responseto the variation in the pseudo-random number data DXA.

The 10-bit words each having the stored word data code read out from thememory 56 are successively arranged to produce the enciphered signalvideo data DXC in the form of 10-bit word sequence data. Accordingly,this results in that the C signal video data DVC are subjected to codeconversion for obtaining 10-bit code in response to the pseudo-randomnumber data DXA with the exception of the forbidden codes and therebyconverted into the enciphered C signal video data DXC in the memory 56.As a result, the enciphered C signal video data DXC do not contain anyforbidden code.

Although each of the random number generating portions 52 and 57connected to the memories 51 and 56, respectively, is operative toproduce the pseudo-random number data DXA to be supplied to the memory51 or 56 in the embodied structures shown in FIGS. 8 and 9, it is alsopossible to have such variations as to cause each of the random numbergenerating portions 52 and 57 to produce, instead of the pseudo-randomnumber data DXA, predetermined genuine random number data to be suppliedto the memory 51 or 56.

FIGS. 11 and 12 show a second embodied structures of the Y dataenciphering portion 41 shown in FIG. 7 and a second embodied structuresof the C data enciphering portion 42 shown in FIG. 7, respectively.

In the case where the enciphering portion 31 shown in FIG. 6 isconstituted with the Y data enciphering portion 41 having the secondembodied structure shown in FIG. 11 and the C data enciphering portion42 having the second embodied structure shown in FIG. 12, the structureof the enciphering portion 31 thus constituted corresponds to anembodiment of apparatus for transmitting.

The second embodied structure shown in FIG. 11 of the Y data encipheringportion 41 is constituted with an adding-subtracting modulo operationunit 61 to which the Y signal video data DVY in the form of 10-bit wordsequence data are supplied and a random number generating portion 62 towhich the key data DEY are supplied.

The random number generating portion 62 is constituted in the samemanner as the random number generating portion 52 shown in FIG. 8. Thecircuit blocks in the random number generating portion 62 correspondingto those in the random number generating portion 52 shown in FIG. 8 aremarked with the references common to FIG. 8 and further descriptionthereof will be omitted. Pseudo-random number data DXA obtained from therandom number generating portion 62 are supplied to theadding-subtracting modulo operation unit 61.

The adding-subtracting modulo operation unit 61 is operative to performadding-subtracting modulo operation, which is necessary for subjectingthe Y signal video data DVY to code conversion for obtaining 10-bit codein response to the pseudo-random number data DXA with the exception ofthe forbidden codes, in use of the fact that information codes of the Ysignal video data DVY in the form of 10-bit word sequence data do notcontain any forbidden code and a range of the information codes isarranged between ranges of the forbidden codes to adjacent to thelatter, and further operative to use converted 10-bit codes which areobtained by the adding-subtracting modulo operation for forming theenciphered Y signal video data DXY. As a result, the Y signal video dataDVY are converted into the enciphered Y signal video data DXY which donot contain any forbidden code.

Taking up 10-bit codes because the Y signal video data DVY isconstituted in the form of 10-bit word sequence data, there are 1024different 10-bit codes from 000h to 3FFh. If these 1024 different 10-bitcodes from 000h to 3FFh are marked successively with code positionnumbers 1 to 1024, the code position number for 10-bit code of each ofthe 10-bit words constituting the enciphered Y signal video data DXY isdetermined by the adding-subtracting modulo operation.

Supposing that Mi represents the code position number for each of theinformation codes of the Y signal video data DVY, Ci represents the codeposition number for each of the information codes of the enciphered Ysignal video data DXY, Ei represents the code position number for eachof the 10-bit code of the pseudo-random number data DXA, N1 representsthe number of the forbidden codes arranged out of one side of the rangeof the information codes of the Y signal video data DVY and N2represents the number of the information codes of the Y signal videodata DVY, the adding-subtracting modulo operation is represented withthe following equation.Ci={(Mi−N1)+Ei} mod N2+N1  (1)

wherein {(Mi−N1)+Ei} mod N2 represents a remainder obtained by dividing{(Mi−N1)+Ei} by N2.

Since the Y signal video data DVY are constituted in the form of 10-bitword sequence data, N1 is equal to the number of the forbidden codes000h to 003h, namely, 4, and N2 is equal to the number obtained bysubtracting the number of the forbidden codes from the total number ofthe 10-bit codes, namely, 1024−8=1016.

In the equation (1) mentioned above, with the subtraction forsubtracting N1 from Mi, the code position number of the information codeof the Y signal video data DVY in the code position range from the codeposition number 5 corresponding to 004h to the code position number 1020corresponding to 3FBh is converted into the code position number in thecode position range from the code position number 1 corresponding to000h to the code position number 1016 corresponding to 3F7h, whichcorrespond to active codes 000h to 1016h, as shown in FIG. 13. Then, themodulo operation, by which the code position number of the 10-bit codeof the pseudo-random number data DXA is added to the code positionnumber converted as mentioned above to produce a sum and a remainder isobtained by dividing the sum by 1016, is performed. Further, with theaddition for adding 4 to the obtained remainder, a code position numberin the code position range from the code position number 5 correspondingto 004h to the code position number 1020 corresponding to 3FBh isobtained and the code position number thus obtained is used as the codeposition number Ci for the information code of the enciphered Y signalvideo data DXY.

Then, in the adding-subtracting modulo operation unit 61, the 10-bitcode corresponding to the code position number Ci obtained by theadding-subtracting modulo operation is used as the information code ofthe enciphered Y signal video data DXY. The information code of theenciphered Y signal video data DXY thus determined is obtained byconverting the information code of the Y signal video data DVY into oneof the codes which do not include the forbidden codes in response to the10-bit code of the pseudo-random number data DXA and therefore theenciphered Y signal video data DXY which are constituted with theinformation codes obtained by the adding-subtracting modulo operation donot contain any forbidden code.

The second embodied structure shown in FIG. 12 of the C data encipheringportion 42 is constituted with an adding-subtracting modulo operationunit 63 to which the C signal video data DVC in the form of 10-bit wordsequence data are supplied and a random number generating portion 64 towhich the key data DEY are supplied.

The random number generating portion 64 is constituted in the samemanner as the random number generating portion 62 shown in FIG. 11. Thecircuit blocks in the random number generating portion 64 correspondingto those in the random number generating portion 62 shown in FIG. 11 aremarked with the references common to FIG. 11 and further descriptionthereof will be omitted. Pseudo-random number data DXA obtained from therandom number generating portion 64 are supplied to theadding-subtracting modulo operation unit 63.

The adding-subtracting modulo operation unit 63 is operative to performadding-subtracting modulo operation, which is necessary for subjectingthe C signal video data DVC to code conversion for obtaining 10-bit codein response to the pseudo-random number data DXA with the exception ofthe forbidden codes, in use of the fact that information codes of the Csignal video data DVC in the form of 10-bit word sequence data do notcontain any forbidden code and a range of the information codes isarranged between ranges of the forbidden codes to adjacent to thelatter. The adding-subtracting modulo operation for the C signal videodata DVC in the adding-subtracting modulo operation unit 63 is carriedout in the similar manner as the adding-subtracting modulo operation forthe Y signal video data DVY carried out in the adding-subtracting modulooperation unit 61 shown in FIG. 11 and converted codes determined by theadding-subtracting modulo operation in the adding-subtracting modulooperation unit 63 are used as the information code of the enciphered Csignal video data DXC.

The information code of the enciphered C signal video data DXCdetermined as mentioned above is obtained by converting the informationcode of the C signal video data DVC into one of the codes which do notinclude the forbidden codes in response to the 10-bit code of thepseudo-random number data DXA and therefore the enciphered C signalvideo data DXC which are constituted with the information codes obtainedby the adding-subtracting modulo operation do not contain any forbiddencode.

Although each of the random number generating portions 62 and 64connected to the adding-subtracting modulo operation units 61 and 63,respectively, is operative to produce the pseudo-random number data DXAto be supplied to the adding-subtracting modulo operation units 61 and63 in the embodied structures shown in FIGS. 11 and 12, it is alsopossible to have such variations as to cause each of the random numbergenerating portions 62 and 64 to produce, instead of the pseudo-randomnumber data DXA, predetermined genuine random number data to be suppliedto the adding-subtracting modulo operation units 61 or 63.

FIGS. 14 and 15 show a third embodied structures of the Y dataenciphering portion 41 shown in FIG. 7 and a third embodied structuresof the C data enciphering portion 42 shown in FIG. 7, respectively.

In the case where the enciphering portion 31 shown in FIG. 6 isconstituted with the Y data enciphering portion 41 having the thirdembodied structure shown in FIG. 14 and the C data enciphering portion42 having the third embodied structure shown in FIG. 15, the structureof the enciphering portion 31 thus, constituted corresponds to anembodiment of apparatus for transmitting.

The third embodied structures shown in FIG. 14 of the Y data encipheringportion 41 is used for the Y signal video data DVY which are composed of10-bit words each having information code extracted from a 10-bit codegroup in which the information codes are mixed with forbidden codeswhich are not set to be 000h to 003h and 3FCh to 3FFh.

Such a third embodied structure as shown in FIG. 14 is constituted byadding a memory 66 to an input end of the adding-subtracting modulooperation unit 61 in the second embodied structure shown in FIG. 11 ofthe Y data enciphering portion 41.

The Y signal video data DVY in the form of 10-bit word sequence data,which are composed of 10-bit words each having the information codeextracted from the 10-bit code group in which the information codes aremixed with the forbidden codes which are not set to be 000h to 003h and3FCh to 3FFh, are supplied to the memory 66. In the memory 66, thewriting and reading of the Y signal video data DVY are carried out andread Y signal video data DVYM based on the Y signal video data DVY aresent from the memory 66.

In the writing of the Y signal video data DVY in the memory 66, each ofthe 10-bit words composing of the Y signal video data DVY is written inthe memory 66 with writing address determined in accordance with 10-bitcode of the 10-bit word to be written and in the reading of the Y signalvideo data DVY from the memory 66, each of the 10-bit word composing ofthe Y signal video data DVY is read from the memory 66 with readingaddress which is put in a specific corresponding relation to the writingaddress. In the specific corresponding relation between the writingaddress and the reading address, for example, the writing addressesallotted to the forbidden codes are positioned out of the range of thewriting addresses allotted to the information codes, as shown witharrowheaded lines in FIG. 16.

With such specific corresponding relation between the writing addressand the reading address, the read Y signal video data DVYM send from thememory 66 by reading the Y signal video data DVY written in the memory66 are constituted in such a manner that the range of the forbiddencodes is arranged out of the range of the information codes to adjacentto the same. This means that the memory 66 is operative to convert the Ysignal video data DVY which are composed of 10-bit words each having theinformation code extracted from the 10-bit code group in which theinformation codes are mixed with the forbidden codes into the read Ysignal video data DVYM which are constituted in such a manner that therange of the forbidden codes is arranged out of the range of theinformation codes to adjacent to the same.

In the read Y signal video data DVYM sent from the memory 66, the rangeof the forbidden codes is arranged out of the range of the informationcodes to adjacent to the same in the same manner as the Y signal videodata DVY supplied to the adding-subtracting modulo operation unit 61 inthe second embodied structure shown in FIG. 11 of the Y data encipheringportion 41, in which the forbidden codes are set to be 000h to 003h and3FCh to 3FFh which are arranged out of the information codes. The read Ysignal video data DVYM thus obtained from the memory 66 are supplied tothe adding-subtracting modulo operation unit 61.

The adding-subtracting modulo operation unit 61 is operative to performadding-subtracting modulo operation for the read Y signal video dataDVYM to produce enciphered Y signal video data DXY. Theadding-subtracting modulo operation for the read Y signal video dataDVYM in the adding-subtracting modulo operation unit 61 is carried outin the similar manner as the adding-subtracting modulo operation for theY signal video data DVY carried out in the adding-subtracting modulooperation unit 61 shown in FIG. 11 and converted codes determined by theadding-subtracting modulo operation in the adding-subtracting modulooperation unit 61 are used as the information code of the enciphered Ysignal video data DXY. As a result, the read Y signal video data DVYMare converted into the enciphered Y signal video data DXY which do notcontain any forbidden code.

As described above, in the third embodied structure shown in FIG. 14 ofthe Y data enciphering portion 41, the Y signal video data DVY areconverted into the read Y signal video data DVYM in the memory 66 andthen the read Y signal video data DVYM are subjected to theadding-subtracting modulo operation in the adding-subtracting modulooperation unit 61 to be converted into the enciphered Y signal videodata DXY.

The third embodied structures shown in FIG. 15 of the C data encipheringportion 42 is used for the C signal video data DVC which are composed of10-bit words each having information code extracted from a 10-bit codegroup in which the information codes are mixed with forbidden codeswhich are not set to be 000h to 003h and 3FCh to 3FFh.

Such a third embodied structure as shown in FIG. 15 is constituted byadding a memory 67 to an input end of the adding-subtracting modulooperation unit 63 in the second embodied structure shown in FIG. 12 ofthe C data enciphering portion 42.

The C signal video data DVC in the form of 10-bit word sequence data,which are composed of 10-bit words each having the information codeextracted from the 10-bit code group in which the information codes aremixed with the forbidden codes which are not set to be 000h to 003h and3FCh to 3FFh, are supplied to the memory 67. In the memory 67, thewriting and reading of the C signal video data DVC are carried out andread C signal video data DVCM based on the C signal video data DVC aresent from the memory 67. The writing and reading of the C signal videodata DVC in the memory 67 are carried out in the similar manner as thewriting and reading of the Y signal video data DVY in the memory 66shown in FIG. 14 and thereby the read C signal video data DVCM, in whicha range of the forbidden codes is arranged out of a range of theinformation codes to adjacent to the same, are sent from the memory 67.This means that the memory 67 is operative to convert the C signal videodata DVC which are composed of 10-bit words each having the informationcode extracted from the 10-bit code group in which the information codesare mixed with the forbidden codes into the read C signal video dataDVCM which are constituted in such a manner that the range of theforbidden codes is arranged out of the range of the information codes toadjacent to the same.

In the read C signal video data DVCM sent from the memory 67, the rangeof the forbidden codes is arranged out of the range of the informationcodes to adjacent to the same in the same manner as the C signal videodata DVC supplied to the adding-subtracting modulo operation unit 63 inthe second embodied structure shown in FIG. 12 of the C data encipheringportion 42, in which the forbidden codes are set to be 000h to 003h and3FCh to 3FFh which are arranged out of the information codes. The read Csignal video data DVCM thus obtained from the memory 67 are supplied tothe adding-subtracting modulo operation unit 63.

The adding-subtracting modulo operation unit 63 is operative to performadding-subtracting modulo operation for the read C signal video dataDVCM to produce enciphered C signal video data DXC. Theadding-subtracting modulo operation for the read C signal video dataDVCM in the adding-subtracting modulo operation unit 63 is carried outin the similar manner as the adding-subtracting modulo operation for theC signal video data DVC carried out in the adding-subtracting modulooperation unit 63 shown in FIG. 12 and converted codes determined by theadding-subtracting modulo operation in the adding-subtracting modulooperation unit 63 are used as the information code of the enciphered Csignal video data DXC. As a result, the read C signal video data DVCMare converted into the enciphered C signal video data DXC which do notcontain any forbidden code.

As described above, in the third embodied structure shown in FIG. 15 ofthe C data enciphering portion 42, the C signal video data DVC areconverted into the read C signal video data DVCM in the memory 67 andthen the read C signal video data DVCM are subjected to theadding-subtracting modulo operation in the adding-subtracting modulooperation unit 63 to be converted into the enciphered C signal videodata DXC.

Although each of the random number generating portions 62 and 64connected to the adding-subtracting modulo operation units 61 and 63,respectively, is operative to produce the pseudo-random number data DXAto be supplied to the adding-subtracting modulo operation units 61 and63 in the embodied structures shown in FIGS. 14 and 15, it is alsopossible to have such variations as to cause each of the random numbergenerating portions 62 and 64 to produce, instead of the pseudo-randomnumber data DXA, predetermined genuine random number data to be suppliedto the adding-subtracting modulo operation units 61 or 63.

FIG. 17 shows an example of a random number generating portion which canbe used in place of the random number generating portion 52 in the firstembodied structure shown in FIG. 8 of the Y data enciphering portion 41,the random number generating portion 57 in the first embodied structureshown in FIG. 9 of the C data enciphering portion 42, the random numbergenerating portion 62 in each of the second and third embodiedstructures shown in FIGS. 11 and 14 of the Y data enciphering portion 41or the random number generating portion 64 in each of the second andthird embodied structures shown in FIGS. 12 and 15 of the C dataenciphering portion 42.

In the random number generating portion 52′ shown in FIG. 17, a counter53′ is operative to count in response to initial input data DIT toproduce counter output data DRZ′ composed of, for example, 128 bits tobe supplied to an AES cipher producing portion 54′.

The AES cipher producing portion 54′ is operative to perform AESenciphering process in accordance with the AES (Advanced EncryptionStandard) published in 2001 by the National Institute of Standards andTechnology, the United State of America.

Key data DEY are also supplied to the AES cipher producing portion 54′.In the AES cipher producing portion 54′, the counter output data DRZ′are subjected to the AES enciphering process in accordance with therules determined by the key data DEY to produce cipher data DEZ′composed of, for example, 128 bits.

The cipher data DEZ′ obtained from the AES cipher producing portion 54′are supplied to a bit extracting portion 55′. The bit extracting portion55′ is operative to extract 10 bits of 128 bits forming the cipher dataDEZ′ as pseudo-random number data DXA′. The pseudo-random number dataDXA′ obtained from the bit extracting portion 55′ are sent from therandom number generating portion 52′ to be used in place of thepseudo-random number data DXA obtained from the random number generatingportion 52 shown in FIG. 8, the random number generating portion 57shown in FIG. 9, the random number generating portion 62 shown in eachof FIGS. 11 and 14 or the random number generating portions 64 shown ineach of FIGS. 12 and 15.

FIGS. 18 and 19 show a fourth embodied structures of the Y dataenciphering portion 41 shown in FIG. 7 and a fourth embodied structuresof the C data enciphering portion 42 shown in FIG. 7, respectively.

In the case where the enciphering portion 31 shown in FIG. 6 isconstituted with the Y data enciphering portion 41 having the fourthembodied structure shown in FIG. 18 and the C data enciphering portion42 having the fourth embodied structure shown in FIG. 19, the structureof the enciphering portion 31 thus constituted corresponds to a secondembodiment of apparatus for transmitting data.

The fourth embodied structure shown in FIG. 18 of the Y data encipheringportion 41 is constituted with an adding-subtracting modulo operationunit 61 to which Y signal video data DVY in the form of 10-bit wordsequence data are supplied and a random number generating portion 70 towhich key data DEY are supplied.

The adding-subtracting modulo operation unit 61 is constituted in thesame manner as the adding-subtracting modulo operation unit 61 shown inFIG. 11 and operative to convert the Y signal video data DVY intoenciphered Y signal video data DXY constituted in the form of 10-bitword sequence data which do not contain any forbidden code in such amanner as aforementioned.

In the random number generating portion 70, a register 71 is operativeto put out, in response to input data, register output data DRZ composedof, for example, 128 bits to be supplied to a DES cipher producingportion 72. Initial input data DIT are supplied to the register 71.

The key data DEY also supplied to the DES cipher producing portion 72.In the DES cipher producing portion 72, the register output data DRZ aresubjected to the DES enciphering process in accordance with the rulesdetermined by the key data DEY to produce cipher data DEZ composed of,for example, 128 bits. The cipher data DEZ obtained from the DES cipherproducing portion 72 are supplied to a bit dividing portion 73.

The bit dividing portion 73 is operative to divide 128 bits composingthe cipher data DEZ into 10 bits and 118 bits to produce pseudo-randomnumber data DXA composed of 10 bits and feedback data DXB composed of118 bits. The pseudo-random number data DXA obtained from the bitdividing portion 73 are sent from the random number generating portion70 to the adding-subtracting modulo operation unit 61. The feedback dataDXB obtained from the bit dividing portion 73 are supplied to a bitadder 74.

The enciphered Y signal video data DXY in the form of 10-bit wordsequence data obtained from the adding-subtracting modulo operation unit61 are also supplied to the bit adder 74. In the bit adder 74, theenciphered Y signal video data DXY in the form of 10-bit word sequencedata are added in bit to the feedback data DXB composed of 118 bits toproduce data DXB+DXY composed of 128 bits. The data DXB+DXY composed of128 bits thus obtained are fed to the register 71 as another input data.Therefore, the register 71 is operative first to put out the registeroutput data DRZ in response to the initial input data DIT and then toput out the register output data DRZ in response to the data DXB+DXYobtained from the bit adder 74.

The fourth embodied structure shown in FIG. 19 of the C data encipheringportion 42 is constituted with an adding-subtracting modulo operationunit 63 to which C signal video data DVC in the form of 10-bit wordsequence data are supplied and a random number generating portion 75 towhich key data DEY are supplied.

The adding-subtracting modulo operation unit 63 is constituted in thesame manner as the adding-subtracting modulo operation unit 63 shown inFIG. 12 and operative to convert the C signal video data DVC intoenciphered C signal video data DXC constituted in the form of 10-bitword sequence data which do not contain any forbidden code in such amanner as aforementioned.

The random number generating portion 75 is constituted with a register71, a DES cipher producing portion 72, a bit dividing portion 73 and abit adder 74 in the same manner as the random number generating portion70 shown in FIG. 18. In the bit adder 74 provided in the random numbergenerating portion 75, the enciphered C signal video data DXC in theform of 10-bit word sequence data obtained from the adding-subtractingmodulo operation unit 61 are added in bit to feedback data DXB composedof 118 bits obtained from the bit dividing portion 73 to produce dataDXB+DXC composed of 128 bits. The other operations of the random numbergenerating portion 75 are the same as those in the random numbergenerating portion 70 shown in FIG. 18.

Although each of the random number generating portions 70 and 75connected to the adding-subtracting modulo operation units 61 and 63,respectively, is operative to produce the pseudo-random number data DXAto be supplied to the adding-subtracting modulo operation units 61 and63 in the embodied structures shown in FIGS. 18 and 19, it is alsopossible to have such variations as to cause each of the random numbergenerating portions 70 and 75 to produce, instead of the pseudo-randomnumber data DXA, predetermined genuine random number data to be suppliedto the adding-subtracting modulo operation units 61 or 63.

FIGS. 20 and 21 show a fifth embodied structures of the Y dataenciphering portion 41 shown in FIG. 7 and a fifth embodied structuresof the C data enciphering portion 42 shown in FIG. 7, respectively.

In the case where the enciphering portion 31 shown in FIG. 6 isconstituted with the Y data enciphering portion 41 having the fifthembodied structure shown in FIG. 20 and the C data enciphering portion42 having the fifth embodied structure shown in FIG. 21, the structureof the enciphering portion 31 thus constituted corresponds to a thirdembodiment of apparatus for transmitting data.

The fifth embodied structure shown in FIG. 20 of the Y data encipheringportion 41 is constituted with an adding-subtracting modulo operationunit 61 to which Y signal video data DVY in the form of 10-bit wordsequence data are supplied and a random number generating portion 76 towhich key data DEY are supplied.

The adding-subtracting modulo operation unit 61 is constituted in thesame manner as the adding-subtracting modulo operation unit 61 shown inFIG. 18 and operative to convert the Y signal video data DVY intoenciphered Y signal video data DXY constituted in the form of 10-bitword sequence data which do not contain any forbidden code in such amanner as aforementioned.

The random number generating portion 76 is constituted with a register71, a DES cipher producing portion 72, a bit dividing portion 73 and abit adder 74 in the same manner as the random number generating portion70 shown in FIG. 18. In the bit adder 74 provided in the random numbergenerating portion 76, the Y signal video data DVY in the form of 10-bitword sequence data which is supplied to the adding-subtracting modulooperation unit 61 are added in bit to feedback data DXB composed of 118bits obtained from the bit dividing portion 73 to produce data DXB+DVYcomposed of 128 bits. The other operations of the random numbergenerating portion 76 are the same as those in the random numbergenerating portion 70 shown in FIG. 18.

The fifth embodied structure shown in FIG. 21 of the C data encipheringportion 42 is constituted with an adding-subtracting modulo operationunit 63 to which C signal video data DVC in the form of 10-bit wordsequence data are supplied and a random number generating portion 77 towhich key data DEY are supplied.

The adding-subtracting modulo operation unit 63 is constituted in thesame manner as the adding-subtracting modulo operation unit 63 shown inFIG. 19 and operative to convert the C signal video data DVC intoenciphered C signal video data DXC constituted in the form of 10-bitword sequence data which do not contain any forbidden code in such amanner as aforementioned.

The random number generating portion 77 is constituted with a register71, a DES cipher producing portion 72, a bit dividing portion 73 and abit adder 74 in the same manner as the random number generating portion75 shown in FIG. 19. In the bit adder 74 provided in the random numbergenerating portion 77, the C signal video data DVC in the form of 10-bitword sequence data which are supplied to the adding-subtracting modulooperation unit 63 are added in bit to feedback data DXB composed of 118bits obtained from the bit dividing portion 73 to produce data DXB+DVCcomposed of 128 bits. The other operations of the random numbergenerating portion 77 are the same as those in the random numbergenerating portion 75 shown in FIG. 19.

Although each of the random number generating portions 76 and 77connected to the adding-subtracting modulo operation units 61 and 63,respectively, is operative to produce pseudo-random number data DXA tobe supplied to the adding-subtracting modulo operation units 61 and 63in the embodied structures shown in FIGS. 20 and 21, it is also possibleto have such variations as to cause each of the random number generatingportions 76 and 77 to produce, instead of the pseudo-random number dataDXA, predetermined genuine random number data to be supplied to theadding-subtracting modulo operation units 61 or 63.

FIG. 22 shows an example of a random number generating portion which canbe used in place of the random number generating portion 70 in thefourth embodied structure shown in FIG. 18 of the Y data encipheringportion 41, the random number generating portion 75 in the fourthembodied structure shown in FIG. 19 of the C data enciphering portion42, the random number generating portion 76 in the fifth embodiedstructures shown in FIG. 20 of the Y data enciphering portion 41 or therandom number generating portion 77 in the fifth embodied structuresshown in FIG. 21 of the C data enciphering portion 42.

In a random number generating portion 70′ shown in FIG. 22, a register71′ produces, in response to initial input data DIT, register outputdata DRZ′ composed of, for example, 128 bits to be supplied to an AEScipher producing portion 72′.

The AES cipher producing portion 72′ is constituted in the same manneras the AES cipher producing portion 54′ in the random number generatingportion 52′ shown in FIG. 17.

Key data DEY are also supplied to the AES cipher producing portion 72′In the AES cipher producing portion 72′, the register output data DRZ′are subjected to the AES enciphering process in accordance with therules determined by the key data DEY to produce cipher data DEZ′composed of, for example, 128 bits. The cipher data DEZ′ obtained fromthe AES cipher producing portion 72′ are supplied to a bit dividingportion 73′.

The bit dividing portion 73′ is operative to divide 128 bits composingthe cipher data DEZ′ into 10 bits and 118 bits to produce pseudo-randomnumber data DXA′ composed of 10 bits and feedback data DXB′ composed of118 bits. The pseudo-random number data DXA′ obtained from the bitdividing portion 73′ are sent from the random number generating portion70′ to be used in place of the pseudo-random number data DXA obtainedfrom the random number generating portion 70 shown in FIG. 18, therandom number generating portion 75 shown in FIG. 19, the random numbergenerating portion 76 shown in FIG. 20 or the random number generatingportion 77 shown in FIG. 21.

The feedback data DXB′ obtained from the bit dividing portion 73′ aresupplied to a bit adder 74′. Enciphered Y signal video data DXY in theform of 10-bit word sequence data are also supplied to the bit adder74′. In the bit adder 74′, the enciphered Y signal video data DXY in theform of 10-bit word sequence data are added in bit to the feedback dataDXB′ composed of 118 bits to produce data DXB′+DXY composed of 128 bits.The data DXB′+DXY composed of 128 bits thus obtained are fed to theregister 71′ as another input data. Therefore, the register 71′ isoperative first to put out the register output data. DRZ′ in response tothe initial input data DIT and then to put out the register output dataDRZ′ in response to the data DXB′+DXY obtained from the bit adder 74′.

FIG. 23 shows, under a condition combined with the embodiment ofapparatus for transmitting data shown in FIG. 6, an embodiment ofapparatus for transmitting data.

The embodiment of apparatus for transmitting data shown in FIG. 6 hasbeen already explained and therefore further description thereof will beomitted.

Referring to FIG. 23, the enciphered HD-SDI signal DXS transmitted fromthe serial data producing portion 33 in the embodiment of apparatus fortransmitting data shown in FIG. 6 is received by parallel data producingportion 81. In the parallel data producing portion 81, the encipheredHD-SDI signal DXS is supplied to an equalizer 82. In the equalizer 82,the enciphered HD-SDI signal DXS are subjected to level-equalization forcompensating for reduction in high frequency components caused on a datatransmission line to produce an equalized enciphered HD-SDI signal DXS′.The equalized enciphered HD-SDI signal DXS′ obtained from the equalizer82 is supplied to both of a NRZI converter 83 and a clock reproducingportion 84. In the clock reproducing portion 84, a clock signal CKcontained in the equalized enciphered HD-SDI signal DXS′ is reproduced.

The clock signal CK obtained from the clock reproducing portion 84 issupplied to the NRZI converter 83 so that NRZI conversion of theequalized enciphered HD-SDI signal DXS′ is carried out with the clocksignal CK in the NRZI converter 83. Therefore, an enciphered HD-SDIsignal DXSC which has been subjected to the NRZI conversion is derivedto be supplied to a descrambling portion 85. The clock signal CKobtained from the clock reproducing portion 84 is also supplied to thedescrambling portion 85. In the descrambling portion 85, the encipheredHD-SDI signal DXSC is descrambled to produce a descrambled encipheredHD-SDI signal DXSD. The descrambled enciphered HD-SDI signal DXSD isderived from the descrambling portion 85 is supplied to both of an S/Pconverter 86 and a word synchronous signal generating portion 87.

The clock signal CK obtained from the clock reproducing portion 84 isalso supplied to the word synchronous signal generating portion 87. Aportion of the descrambled enciphered HD-SDI signal DXSD, whichcorresponds to serial data converted from the timing identificationcodes arranged in order of 3FFh, 000h, 000h for constituting the timereference code data SAV or EAV, is detected with the clock signal CK anda word synchronous signal SWS is produced in response to the detectionof the aforementioned portion, in the word synchronous signal generatingportion 87. The word synchronous signal SWS obtained from the wordsynchronous signal generating portion 87 is supplied to the S/Pconverter 86. The clock signal CK obtained from the clock reproducingportion 84 is also supplied to the S/P converter 86 and the descrambledenciphered HD-SDI signal DXSD is subjected to S/P conversion under thecondition of word-synchronization according to the word synchronoussignal SWS in the S/P converter 86. With the S/P conversion thusprocessed, the descrambled enciphered HD-SDI signal DXSD is convertedinto enciphered 20-bit word sequence data DXP which are constituted withthe enciphered Y and P_(B)/P_(R) data sequences each forming 10-bit wordsequence data and multiplexed bit by bit with their time reference codedata SAV and EAV synchronizing with each other.

The enciphered 20-bit word sequence data DXP obtained from the S/Pconverter 86 are supplied to a data dividing portion 88. In the datadividing portion 88, the enciphered 20-bit word sequence data DXP aredivided into the multiple time reference data DAV, the multipleancillary data DAA and the enciphered video data DXI. The multiple timereference data DAV are obtained in the form of 20-bit word sequence dataconstituted with the time reference code data SAV and EAV, the linenumber data, the error detection code data and so on in the Y datasequence in the form of 10-bit word sequence data and the time referencecode data SAV and EAV, the line number data, the error detection codedata and so on in the P_(B)/P_(R) data sequence in the form of 10-bitword sequence data which are multiplexed bit by bit under the conditionof word-synchronization. The multiple ancillary data DAA are obtained inthe form of 20-bit word sequence data constituted with the ancillarydata in the Y data sequence in the form of 10-bit word sequence data andthe ancillary data in the P_(B)/P_(R) data sequence in the form of10-bit word sequence data which are multiplexed bit by bit under thecondition of word-synchronization. The enciphered video data DXI areobtained in the form of 20-bit word sequence data containing the Ysignal video data DVY constituting the video data portion in the Y datasequence in the form of 10-bit word sequence data and the C signal videodata DVC constituting the video data portion in the P_(B)/P_(R) datasequence in the form of 10-bit word sequence data which are multiplexedbit by bit under the condition of word-synchronization.

The multiple time reference data DAV, the multiple ancillary data DAAand the enciphered video data DXI obtained from the data dividingportion 88 are sent from the parallel data producing portion 81 to adeciphering processor 89. The deciphering processor 89 is constitutedwith a deciphering portion 90 and a key data generating portion 91.

The multiple time reference data DAV and the multiple ancillary data DAApass through the deciphering processor 89 to be supplied to a serialdata producing portion 92. The enciphered video data DXI are supplied tothe deciphering portion 90 in the deciphering processor 89. The key datagenerating portion 91 is operative to supply the deciphering portion 90with predetermined key data DEY. The key data DEY obtained from the keydata generating portion 91 are of the same contents as those of the keydata DEY obtained from the key data generating portion in the embodimentof apparatus for transmitting data shown in FIG. 6.

In the deciphering portion 90, the enciphered video data DXI in the formof 20-bit word sequence data are subjected to, for example, the DESdeciphering process in accordance with the rules determined by the keydata DEY to produce the multiple video data DVI in the form of 20-bitWord sequence data.

FIG. 24 shows an embodied structure of the deciphering portion 90.

In the embodied structure shown in FIG. 24, the enciphered video dataDXI in the form of 20-bit word sequence data are supplied to a bitdividing portion 100. In the bit dividing portion 100, the encipheredvideo data DXI are divided into the enciphered Y signal video data DXYin the form of 10-bit word sequence data and the enciphered C signalvideo data DXC in the form of 10-bit word sequence data, which areseparately sent from the bit dividing portion 100.

The enciphered Y signal video data DXY and the enciphered C signal videodata DXC obtained from the bit dividing portion 100 are supplied to a Ydata deciphering portion 101 and a C data deciphering portion 102,respectively. The key data DEY obtained from the key data generatingportion 91 are also supplied to both of the Y data deciphering portion101 and the C data deciphering portion 102.

In the Y data deciphering portion 101, the enciphered Y signal videodata DXY in the form of 10-bit word sequence data are subjected to theDES deciphering process in accordance with the rules determined by thekey data DEY to produce the Y signal video data DVY in the form of10-bit word sequence data. In the C data deciphering portion 102, theenciphered C signal video data DXC in the form of 10-bit word sequencedata are subjected to the DES deciphering process in accordance with therules determined by the key data DEY to produce the C signal video dataDVC in the form of 10-bit word sequence data.

The Y signal video data DVY in the form of 10-bit word sequence data andthe C signal video data DVC in the form of 10-bit word sequence datathus obtained from the Y data deciphering portion 101 and the C datadeciphering portion 102, respectively, are supplied to a bit multiplexer103.

In the bit multiplexer 103, the Y signal video data DVY in the forth of10-bit word sequence data and the C signal video data DVC in the form of10-bit word sequence data are multiplexed with each other to produce themultiple video data DVI in the form of 20-bit word sequence data to besent from the deciphering portion 90 as output data.

The multiple video data DVI as the output data from the decipheringportion 90 are sent from the deciphering processor 89 to the serial dataproducing portion 92. In the serial data producing portion 92, themultiple time reference data DAV and the multiple ancillary data DAAeach having passed through the deciphering portion 90 and the Multiplevideo data DVI are supplied to a data multiplexer 104.

In the data multiplexer 104, the multiple video data DVI, the multipletime reference data DAV and the multiple ancillary data DAA aresubjected to multiplexing process to reproduce the 20-bit word sequencedata DHP including the multiple video data DVI, the multiple timereference data DAV and the multiple ancillary data DAA. The 20-bit wordsequence data DHP thus obtained in the data multiplexer 104 are suppliedto a P/S converter 105.

In the P/S converter 105, the 20-bit word sequence data DHP aresubjected to P/S conversion to reproduce the serial data DHSD based onthe 20-bit word sequence data DHP to be supplied to a scrambling portion106.

In the scrambling portion 106, the serial data DHSD are subjected toscrambling process to reproduce the scrambled serial data DHSC to besupplied to a NRZI converter 108. In the NRZI converter 108, thescrambled serial data DHSC are subjected to NRZI conversion to reproducethe HD-SDI signal DHS. The HD-SDI signal DHS thus reproduced in the NRZIconverter 108 is obtained from the serial data producing portion 92.

FIGS. 25 and 26 show a first embodied structures of the Y datadeciphering portion 101 shown in FIG. 24 and a first embodied structuresof the C data deciphering portion 102 shown in FIG. 24, respectively.

In the case where the deciphering portion 90 shown in FIG. 24 isconstituted with the Y data deciphering portion 101 having the firstembodied structure shown in FIG. 25 and the C data deciphering portion102 having the first embodied structure shown in FIG. 26, the structureof the deciphering portion 90 thus constituted corresponds to a firstembodiment of apparatus for transmitting data.

The first embodied structure shown in FIG. 25 of the Y data decipheringportion 101 is constituted with a memory 111 to which the enciphered Ysignal video data DXY in the form of 10-bit word sequence data aresupplied as first reading address data and a random number generatingportion 112 to which the key data DEY are supplied.

The random number generating portion 112 is constituted with a register53, a DES cipher producing portion 54 and a bit extracting portion 55 inthe same manner as the random number generating portion 52 shown in FIG.8 and produces pseudo-random number data DXA to be supplied to thememory 111 as second reading address data.

1016 (1024−8) 10-bit words having respectively different 10-bit codeswith the exception of the forbidden codes 000h to 003h and 3FCh to 3FFhare stored in the memory 111. The 10-bit code of each of 1016 10-bitwords is in a specific corresponding relation to the 10-bit code of eachof the 10-bit words constituting the enciphered Y signal video data DXYwhich are supplied to the memory 111 as the first reading address data,and under such specific corresponding relation, 1016 10-bit words areread from the memory 111 in response to the enciphered Y signal videodata DXY and the specific corresponding relation between the 10-bit codeof each of 1016 10-bit words and the 10-bit code of each of the 10-bitwords constituting the enciphered Y signal video data DXY varies inresponse to the pseudo-random number data DXA supplied to the memory 111as the second reading address data.

The 10-bit words thus read from the memory 111 are successively arrangedto produce the Y signal video data DVY in the form of 10-bit wordsequence data.

The first embodied structure shown in FIG. 26 of the C data decipheringportion 102 is constituted with a memory 116 to which the enciphered Csignal video data DXC in the form of 10-bit word sequence data aresupplied as first reading address data and a random number generatingportion 117 to which the key data DEY are supplied.

The random number generating portion 117 is constituted with a register53, a DES cipher producing portion 54 and a bit extracting portion 55 inthe same manner as the random number generating portion 112 shown inFIG. 25 and produces pseudo-random number data DXA to be supplied to thememory 116 as second reading address data.

1016 (1024−8) 10-bit words having respectively different 10-bit codeswith the exception of the forbidden codes 000h to 003h and 3FCh to 3FFhare stored also in the memory 116. The 10-bit code of each of 101610-bit words is in a specific corresponding relation to the 10-bit codeof each of the 10-bit words constituting the enciphered C signal videodata DXC which are supplied to the memory 116 as the first readingaddress data, and under such specific corresponding relation, 101610-bit words are read from the memory 116 in response to the encipheredC signal video data DXC and the specific corresponding relation betweenthe 10-bit code of each of 1016 10-bit words and the 10-bit code of eachof the 10-bit words constituting the enciphered C signal video data DXCvaries in response to the pseudo-random number data DXA supplied to thememory 116 as the second reading address data.

The 10-bit words thus read from the memory 116 are successively arrangedto produce the C signal video data DVC in the form of 10-bit wordsequence data.

Although each of the random number generating portions 112 and 117connected to the memories 111 and 116, respectively, is operative toproduce the pseudo-random number data DXA to be supplied to the memory111 or 116 in the embodied structures shown in FIGS. 25 and 26, it isalso possible to have such variations as to cause each of the randomnumber generating portions 112 and 117 to produce, instead of thepseudo-random number data DXA, predetermined genuine random number datato be supplied to the memory 111 or 116.

FIGS. 27 and 28 show a second embodied structures of the Y datadeciphering portion 101 shown in FIG. 24 and a second embodiedstructures of the C data deciphering portion 102 shown in FIG. 24,respectively.

In the case where the deciphering portion 90 shown in FIG. 23 isconstituted with the Y data deciphering portion 101 having the secondembodied structure shown in FIG. 27 and the C data deciphering portion102 having the second embodied structure shown in FIG. 28, the structureof the deciphering portion 90 thus constituted corresponds to anembodiment of apparatus for transmitting data.

The second embodied structure shown in FIG. 27 of the Y data decipheringportion 101 is constituted with an adding-subtracting modulo operationunit 121 to which the enciphered Y signal video data DXY in the form of10-bit word sequence data are supplied and a random number generatingportion 122 to which the key data DEY are supplied.

The random number generating portion 122 is constituted with a register53, a DES cipher producing portion 54 and a bit extracting portion 55 inthe same manner as the random number generating portion 112 shown inFIG. 25 and produces pseudo-random number data DXA to be supplied to theadding-subtracting modulo operation unit 121.

The adding-subtracting modulo operation unit 121 is operative to convertthe enciphered Y signal video data DXY into the Y signal video data DVY.In the adding-subtracting modulo operation unit 121, the enciphered Ysignal video data DXY is subjected to adding-subtracting modulooperation in response to the pseudo-random number data DXA and convertedcodes which are determined in accordance with the result of theadding-subtracting modulo operation are used for information code of theY signal video data DVY so that the enciphered Y signal video data DXYare converted into the Y signal video data DVY.

Taking up 10-bit codes because the enciphered Y signal video data DXY isconstituted in the form of 10-bit word sequence data, there are 1024different 10-bit codes from 000h to 3FFh. If these 1024 different 10-bitcodes from 000h to 3FFh are marked successively with code positionnumbers 1 to 1024, the code position number for 10-bit code of each ofthe 10-bit words constituting the Y signal video data DVY is determinedby the adding-subtracting modulo operation.

Supposing that Ci represents the code position number for each of theinformation codes of the enciphered Y signal video data DXY, Mirepresents the code position number for each of the information codes ofthe Y signal video data DVY, Ei represents the code position number foreach of the 10-bit code of the pseudo-random number data DXA, N1represents the number of the forbidden codes arranged out of one side ofthe range of the information codes of the Y signal video data DVY and N2represents, the number of the information codes of the Y signal videodata DVY, the adding-subtracting modulo operation is represented withthe following equation.Mi={(Ci−N1)+Ei} mod N2+N1  (2)

Wherein {(Ci−N1)+Ei} mod N2 represents a remainder obtained by dividing{(Ci−N1)+Ei} by N2.

Since the Y signal video data DVY are constituted in the form of 10-bitword sequence data, N1 is equal to the number of the forbidden codes000h to 003h, namely, 4, and N2 is equal to the number obtained bysubtracting the number of the forbidden codes from the total number ofthe 10-bit codes, namely, 1024−8=1016.

In the equation (2) mentioned above, with the subtraction forsubtracting N1 from Ci, the code position number of the information codeof the enciphered Y signal video data DXY is reduced by 4 to be aconverted code position number. Then, the modulo operation, by which thecode position number of the 10-bit code of the pseudo-random number dataDXA is subtracted from the converted code position number to produce adifference and a remainder is obtained by dividing the difference by1016, is performed. Further, a code position number is determined byadding 4 to the obtained remainder and the code position number thusdetermined is used as the code position number Mi for the informationcode of the Y signal video data DVY.

Then, in the adding-subtracting modulo operation unit 121, the 10-bitcode corresponding to the code position number Mi obtained by theadding-subtracting modulo operation is used as the information code ofthe Y signal video data DVY.

The second embodied structure shown in FIG. 28 of the C data decipheringportion 102 is constituted with an adding-subtracting modulo operationunit 123 to which the enciphered C signal video data DXC in the form of10-bit word sequence data are supplied and a random number generatingportion 124 to which the key data DEY are supplied.

The random number generating portion 124 is constituted with register53, a DES cipher producing portion 54 and a bit extracting portion 55 inthe same manner as the random number generating portion 122 shown inFIG. 27 and produces pseudo-random number data DXA to be supplied to theadding-subtracting modulo operation unit 123.

The adding-subtracting modulo operation unit 123 is operative to convertthe enciphered C signal video data DXC into the C signal video data DVC.In the adding-subtracting modulo operation unit 123, the enciphered Csignal video data DXC is subjected to adding-subtracting modulooperation in response to the pseudo-random number data DXA and convertedcodes which are determined in accordance with the result of theadding-subtracting modulo operation are used for information code of theC signal video data DVC so that the enciphered C signal video data DXCare converted into the C signal video data DVC. This adding-subtractingmodulo operation for the enciphered C signal video data DXC is performedin the similar manner as the adding-subtracting modulo operation for theenciphered Y signal video data DXY performed in the adding-subtractingmodulo operation unit 121 shown in FIG. 27.

Although each of the random number generating portions 122 and 124connected to the adding-subtracting modulo operation units 121 and 123,respectively, is operative to produce the pseudo-random number data DXAto be supplied to the adding-subtracting modulo operation units 121 and123 in the embodied structures shown in FIGS. 27 and 28, it is alsopossible to have such variations as to cause each of the random numbergenerating portions 122 and 124 to produce, instead of the pseudo-randomnumber data DXA, predetermined genuine random number data to be suppliedto the adding-subtracting modulo operation unit 121 or 123.

FIGS. 29 and 30 show a third embodied structures of the Y datadeciphering portion 101 shown in FIG. 24 and a third embodied structuresof the C data deciphering portion 102 shown in FIG. 24, respectively.

In the case where the deciphering portion 90 shown in FIG. 23 isconstituted with the Y data deciphering portion 101 having the thirdembodied structure shown in FIG. 29 and the C data deciphering portion102 having the third embodied structure shown in FIG. 30, the structureof the deciphering portion 90 thus constituted corresponds to anembodiment of apparatus for transmitting data.

The third embodied structures shown in FIG. 29 of the Y data decipheringportion 101 is used for the Y signal video data DVY which are composedof 10-bit words each having information code extracted from a 10-bitcode group in which the information codes are mixed with forbidden codeswhich are not set to be 000h to 003h and 3FCh to 3FFh.

Such a third embodied structure as shown in FIG. 29 is constituted byadding a memory 126 to an output end of the adding-subtracting modulooperation unit 121 in the second embodied structure shown in FIG. 27 ofthe Y data deciphering portion 101.

Each of the adding-subtracting modulo operation unit 121 and the randomnumber generating portion 122 operates in the similar manner as each ofthe adding-subtracting modulo operation unit 121 and the random numbergenerating portion 122 in the second embodied structures shown in FIG.27 of the Y data deciphering portion 101 and the Y signal video dataDVY′ based on the enciphered Y signal video data DXY are Obtained fromthe adding-subtracting modulo operation unit 121. This Y signal videodata DVY′ corresponds to the Y signal video data DVY obtained from theadding-subtracting modulo operation unit 121 in the second embodiedstructures shown in FIG. 27 of the Y data deciphering portion 101, forwhich the range of the forbidden codes is arranged out of the range ofthe information codes.

The Y signal video data DVY′ obtained from the adding-subtracting modulooperation unit 121 are supplied to the memory 126. In the memory 126,the writing and reading of the Y signal video data DVY′ are carried outand the Y signal video data DVY based on the Y signal video data DVY′are sent from the memory 126.

In the writing of the Y signal video data DVY′ in the memory 126, eachof the 10-bit words composing of the Y signal video data DVY′ is writtenin the memory 126 with writing address determined in accordance with10-bit code of the 10-bit word to be written and in the reading of the Ysignal video data DVY′ from the memory 126, each of the 10-bit wordcomposing of the Y signal video data DVY′ is read from the memory 126with reading address which is put in a specific corresponding relationto the writing address. In the specific corresponding relation betweenthe writing address and the reading address, for example, the writingaddresses allotted to the forbidden codes are dispersed in the range ofthe writing addresses allotted to the information codes.

With such specific corresponding relation between the writing addressand the reading address, the Y signal video data DVY send from thememory 126 by reading the Y signal video data DVY′ written in the Memory126 are composed of the 10-bit words each having the information codeextracted from the 10-bit code group in which the information codes aremixed with forbidden codes which are not set to be 000h to 003h and 3FChto 3FFh.

As described above, in the third embodied structure shown in FIG. 29 ofthe Y data deciphering portion 101, the enciphered Y signal video dataDXY is subjected to the adding-subtracting Modulo operation in theadding-subtracting modulo operation unit 121 to be converted into the Ysignal video data DVY′ and then the Y signal video data DVY′ are furthersubjected to the aforementioned data conversion in the memory 126 toreproduce the Y signal video data DVY.

The third embodied structures shown in FIG. 30 of the C data decipheringportion 102 is used for the C signal video data DVC which are composedof 10-bit words each having information code extracted from a 10-bitcode group in which the information codes are mixed with forbidden codeswhich are not set to be 000h to 003h and 3FCh to 3FFh.

Such a third embodied structure as shown in FIG. 30 is constituted byadding a memory 127 to an output end of the adding-subtracting modulooperation unit 123 in the second embodied structure shown in FIG. 28 ofthe C data deciphering portion 102.

Each of the adding-subtracting modulo operation unit 123 and the randomnumber generating portion 124 operates in the similar manner as each ofthe adding-subtracting modulo operation unit 123 and the random numbergenerating portion 124 in the second embodied structures shown in FIG.28 of the C data deciphering portion 102 and the C signal video dataDVC′ based on the enciphered C signal video data DXC are obtained fromthe adding-subtracting modulo operation unit 123. This C signal videodata DVC′ corresponds to the C signal video data DVC obtained from theadding-subtracting modulo operation unit 123 in the second embodiedstructures shown in FIG. 28 of the C data deciphering portion 102, forwhich the range of the forbidden codes is arranged out of the range ofthe information codes.

The C signal video data DVC′ obtained from the adding-subtracting modulooperation unit 123 are supplied to the memory 127. In the memory 127,the writing and reading of the C signal video data DVC′ are carried outand the C signal video data DVC based on the C signal video data DVC′are sent from the memory 127.

In the writing of the C signal video data DVC′ in the memory 127, eachof the 10-bit words composing of the C signal video data DVC′ is writtenin the memory 127 with writing address determined in accordance with10-bit code of the 10-bit word to be written and in the reading of the Csignal video data DVC′ from the memory 127, each of the 10-bit wordcomposing of the C signal video data DVC′ is read from the memory 127with reading address which is put in a specific corresponding relationto the writing address. In the specific corresponding relation betweenthe writing address and the reading address, for example, the writingaddresses allotted to the forbidden codes are dispersed in the range ofthe writing addresses allotted to the information codes.

With such specific corresponding relation between the writing addressand the reading address, the C signal video data DVC send from thememory 127 by reading the C signal video data DVC′ written in the memory127 are composed of the 10-bit words each having the information codeextracted from the 10-bit code group in which the information codes aremixed with forbidden codes which are not set to be 000h to 003h and 3FChto 3FFh.

As described above, in the third embodied structure shown in FIG. 30 ofthe C data deciphering portion 102, the enciphered C signal video dataDXC is subjected to the adding-subtracting modulo operation in theadding-subtracting modulo operation unit 123 to be converted into the Csignal video data DVC′ and then the C signal video data DVC′ are furthersubjected to the aforementioned data conversion in the memory 127 toreproduce the C signal video data DVC.

Although each of the random number generating portions 122 and 124connected to the adding-subtracting modulo operation units 121 and 123,respectively, is operative to produce the pseudo-random number data DXAto be supplied to the adding-subtracting modulo operation units 121 and123 in the embodied structures shown in FIGS. 29 and 30, it is alsopossible to have such variations as to cause each of the random numbergenerating portions 122 and 124 to produce, instead of the pseudo-randomnumber data DXA, predetermined genuine random number data to be suppliedto the adding-subtracting modulo operation unit 121 or 123.

FIG. 31 shows an example of a random number generating portion which canbe used in place of the random number generating portion 112 in thefirst embodied structure shown in FIG. 25 of the Y data decipheringportion 101, the random number generating portion 117 in the firstembodied structure shown in FIG. 26 of the C data deciphering portion102, the random number generating portion 122 in each of the second andthird embodied structures shown in FIGS. 27 and 29 of the Y datadeciphering portion 101 or the random number generating portion 124 ineach of the second and third embodied structures shown in FIGS. 28 and30 of the C data deciphering portion 102.

The random number generating portion 112′ shown in FIG. 31 isconstituted in the same manner as the random number generating portion52′ shown in FIG. 17 and further description thereof will be omitted.Pseudo-random number data DXA′ obtained from the random numbergenerating portion 112′ are used in place of the pseudo-random numberdata DXA obtained from each of the random number generating portion 112in the first embodied structure shown in FIG. 25 of the Y datadeciphering portion 101, the random number generating portion 117 in thefirst embodied structure shown in FIG. 26 of the C data decipheringportion 102, the random number generating portion 122 in each of thesecond and third embodied structures shown in FIGS. 27 and 29 of the Ydata deciphering portion 101 and the random number generating portion124 in each of the second and third embodied structures shown in FIGS.28 and 30 of the C data deciphering portion 102.

FIGS. 32 and 33 show a fourth embodied structures of the Y datadeciphering portion 101 shown in FIG. 24 and a fourth embodiedstructures of the C data deciphering portion 102 shown in FIG. 24;respectively.

In the case where the deciphering portion 90 shown in FIG. 23 isconstituted with the Y data deciphering portion 101 having the fourthembodied structure shown in FIG. 32 and the C data deciphering portion102 having the fourth embodied structure shown in FIG. 33, the structureof the deciphering portion 90 thus constituted corresponds to a secondembodiment of apparatus for transmitting data.

The fourth embodied structure shown in FIG. 32 of the Y data decipheringportion 101 is constituted with an adding-subtracting modulo operationunit 121 to which the enciphered Y signal video data DXY in the form of10-bit word sequence data are supplied and a random number generatingportion 130 to which key data DEY are supplied.

The adding-subtracting modulo operation unit 121 is constituted in thesame manner as the adding-subtracting modulo operation unit 121 shown inFIG. 27 and operative to convert the enciphered Y signal video data DXYinto the Y signal video data DVY constituted in the form of 10-bit wordsequence data in such a manner as aforementioned.

In the random number generating portion 130, a register 131 is operativeto put out, in response to input data, register output data DRZ composedof, for example, 128 bits to be supplied to a DES cipher producingportion 132. Initial input data DIT are supplied to the register 131.

The key data DEY also supplied to the DES cipher producing portion 132.In the DES cipher producing portion 132, the register output data DRZare subjected to the DES enciphering process in accordance with therules determined by the key data DEY to produce cipher data DEZ composedof, for example, 128 bits. The cipher data DEZ obtained from the DEScipher producing portion 132 are supplied to a bit dividing portion 133.

The bit dividing portion 133 is operative to divide 128 bits composingthe cipher data DEZ into 10 bits and 118 bits to produce pseudo-randomnumber data DXA composed of 10 bits and feedback data DXB composed of118 bits. The pseudo-random number data DXA obtained from the bitdividing portion 73 are sent from the random number generating portion130 to the adding-subtracting modulo operation unit 121. The feedbackdata DXB obtained from the bit dividing portion 133 are supplied to abit adder 134.

The enciphered Y signal video data DXY in the form of 10-bit wordsequence data which are supplied to the adding-subtracting modulooperation unit 121 are also supplied to the bit adder 134. In the bitadder 134, the enciphered Y signal video data DXY in the form of 10-bitword sequence data are added in bit to the feedback data DXB composed of118 bits to produce data DXB+DXY composed of 128 bits. The data DXB+DXYcomposed of 128 bits thus obtained are fed to the register 131 asanother input data. Therefore, the register 131 is operative first toput out the register output data DRZ in response to the initial inputdata DIT and then to put out the register output data DRZ in response tothe data DXB+DXY obtained from the bit adder 134.

The fourth embodied structure shown in FIG. 33 of the C data decipheringportion 102 is constituted with an adding-subtracting modulo operationunit 123 to which the enciphered C signal video data DXC in the form of10-bit word sequence data are supplied and a random number generatingportion 135 to which key data DEY are supplied.

The adding-subtracting modulo operation unit 123 is constituted in thesame manner as the adding-subtracting modulo operation unit 123 shown inFIG. 28 and operative to convert the enciphered C signal video data DXCinto the C signal video data DVC constituted in the form of 10-bit wordsequence data in such a manner as aforementioned.

The random number generating portion 135 is constituted with a register131; a DES cipher producing portion 132, a bit dividing portion 133 anda bit adder 134 in the same manner as the random number generatingportion 130 shown in FIG. 32. In the bit adder 134 provided in therandom number generating portion 135, the enciphered C signal video dataDXC in the form of 10-bit word sequence data which are supplied also tothe adding-subtracting modulo operation unit 123 are added in bit tofeedback data DXB composed of 118 bits obtained from the bit dividingportion 133 to produce data DXB+DXC composed of 128 bits. The otheroperations of the random number generating portion 135 are the same asthose in the random number generating portion 130 shown in FIG. 32.

Although each of the random number generating portions 130 and 135connected to the adding-subtracting modulo operation units 121 and 123,respectively, is operative to produce the pseudo-random number data DXAto be supplied to the adding-subtracting modulo operation units 121 and123 in the embodied structures shown in FIGS. 32 and 33, it is alsopossible to have such variations as to cause each of the random numbergenerating portions 130 and 135 to produce, instead of the pseudo-randomnumber data DXA, predetermined genuine random number data to be suppliedto the adding-subtracting modulo operation unit 121 or 123.

FIGS. 34 and 35 show a fifth embodied structures of the Y datadeciphering portion 101 shown in FIG. 24 and a fifth embodied structuresof the C data deciphering portion 102 shown in FIG. 24, respectively.

In the case where the deciphering portion 90 shown in FIG. 23 isconstituted with the Y data deciphering portion 101 having the fifthembodied structure shown in FIG. 34 and the C data deciphering portion102 having the fifth embodied structure shown in FIG. 35, the structureof the deciphering portion 90 thus constituted corresponds to a thirdembodiment of apparatus for transmitting data.

The fifth embodied structure shown in FIG. 34 of the Y data decipheringportion 101 is constituted with an adding-subtracting modulo operationunit 121 to which the enciphered Y signal video data DXY in the forth of10-bit word sequence data are supplied and a random number generatingportion 136 to which key data DEY are supplied.

The adding-subtracting modulo operation unit 121 is constituted in thesame manner as the adding-subtracting modulo operation unit 121 shown inFIG. 32 and operative to convert the enciphered Y signal video data DXYinto the Y signal video data DVY constituted in the form of 10-bit wordsequence data in such a manner as aforementioned.

The random number generating portion 136 is constituted with a register131, a DES cipher producing portion 132, a bit dividing portion 133 anda bit adder 134 in the same manner as the random number generatingportion 130 shown in FIG. 32. In the bit adder 134 provided in therandom number generating portion 136, the Y signal video data DVY in theform of 10-bit word sequence data obtained from to theadding-subtracting modulo operation unit 121 are added in bit tofeedback data DXB composed of 118 bits obtained from the bit dividingportion 133 to produce data DXB+DVY composed of 128 bits. The otheroperations of the random number generating portion 136 are the same asthose in the random number generating portion 130 shown in FIG. 32.

The fifth embodied structure shown in FIG. 35 of the C data decipheringportion 102 is constituted with an adding-subtracting modulo operationunit 123 to which the enciphered C signal video data DXC in the form of10-bit word sequence data are supplied and a random number generatingportion 137 to which key data DEY are supplied.

The adding-subtracting modulo operation unit 123 is constituted in thesame manner as the adding-subtracting modulo operation unit 123 shown inFIG. 33 and operative to convert the enciphered C signal video data DXCinto the C signal video data DVC constituted in the form of 10-bit wordsequence data in such a manner as aforementioned.

The random number generating portion 137 is constituted with a register131, a DES cipher producing portion 132, a bit dividing portion 133 anda bit adder 134 in the same manner as the random number generatingportion 135 shown in FIG. 33. In the bit adder 134 provided in therandom number generating portion 137, the C signal video data DVC in theform of 10-bit word sequence data obtained from the adding-subtractingmodulo operation unit 123 are added in bit to feedback data DXB composedof 118 bits obtained from the bit dividing portion 133 to produce dataDXB DVC composed of 128 bits. The other operations of the random numbergenerating portion 137 are the same as those in the random numbergenerating portion 135 shown in FIG. 33.

Although each of the random number generating portions 136 and 137connected to the adding-subtracting modulo operation units 121 and 123,respectively, is operative to produce pseudo-random number data DXA tobe supplied to the adding-subtracting modulo operation units 121 and 123in the embodied structures shown in FIGS. 34 and 35, it is also possibleto have such variations as to cause each of the random number generatingportions 136 and 137 to produce, instead of the pseudo-random numberdata DXA, predetermined genuine random number data to be supplied to theadding-subtracting modulo operation unit 121 or 123.

FIG. 36 shows an example of a random number generating portion which canbe used in place of the random number generating portion 130 in thefourth embodied structure shown in FIG. 32 of the Y data decipheringportion 101, the random number generating portion 135 in the fourthembodied structure shown in FIG. 33 of the C data deciphering portion102, the random number generating portion 136 in the fifth embodiedstructures shown in. FIG. 34 of the Y data deciphering portion 101 orthe random number generating portion 137 in the fifth embodiedstructures shown in FIG. 35 of the C data deciphering portion 102.

In the random number generating portion 130′ shown in FIG. 36, register131′ produces, in response to initial input data DIT, register outputdata DRZ′ composed of, for example, 128 bits to be supplied to an AEScipher producing portion 132′.

The AES cipher producing portion 132′ is constituted in the same manneras the AES cipher producing portion 54′ in the random number generatingportion 52′ shown in FIG. 17.

Key data DEY are also supplied to the AES cipher producing portion 132′.In the AES cipher producing portion 132′, the register output data DRZ′are subjected to the AES enciphering process in accordance with therules determined by the key data DEY to produce cipher data DEZ′composed of, for example, 128 bits. The cipher data DEZ′ obtained fromthe AES cipher producing portion 132′ are supplied to a bit dividingportion 133′.

The bit dividing portion 133′ is operative to divide 128 bits composingthe cipher data DEZ′ into 10 bits and 118 bits to produce pseudo-randomnumber data DXA′ composed of 10 bits and feedback data DXB′ composed of118 bits. The pseudo-random number data DXA′ obtained from the bitdividing portion 133′ are sent from the random number generating portion130′ to be used in place of the pseudo-random number data DXA obtainedfrom the random number generating portion 130 shown in FIG. 32, therandom number generating portion 135 shown in FIG. 33, the random numbergenerating portion 136 shown in FIG. 34 or the random number generatingportion 137 shown in FIG. 35.

The feedback data DXB′ obtained from the bit dividing portion 133′ aresupplied to a bit adder 134′. The enciphered Y signal video data DXY inthe form of 10-bit word sequence data are also supplied to the bit adder134′. In the bit adder 74′, the enciphered Y signal video data DXY inthe form of 10-bit word sequence data are added in bit to the feedbackdata DXB′ composed of 118 bits to produce data DXB′+DXY composed of 128bits. The data DXB′+DXY composed of 128-bits thus obtained are fed tothe register 131′ as another input data. Therefore, the register 131′ isoperative first to put out the register output data DRZ′ in response tothe initial input data DIT and then to put out the register output dataDRZ′ in response to the data DXB′+DXY obtained from the bit adder 134′.

Although the serial data are transmitted from the apparatus fortransmitting data shown in FIG. 6, in which the enciphering process iscarried out, to the apparatus for transmitting data shown in FIG. 23, inwhich the deciphering process is carried out, in the embodimentsmentioned above, the method of or the apparatus for transmitting data.

Applicability for Industrial Use

As apparent from the above description, with the method of transmittingdata according to the invention or the apparatus for transmitting dataaccording to the invention, digital information data contained in wordsequence data which contain also time reference code data constitutedwith timing identification codes in addition to the digital informationdata are subjected to enciphering process in such a manner as not toproduce forbidden code for producing enciphered digital information datawhich do not contain any forbidden code, and the enciphered digitalinformation data and the time reference code data are multiplexed witheach other to produce enciphered word sequence data to be transmitted.Thereby, when the enciphered word sequence data to be transmitted areconverted into enciphered serial data, the enciphered serial data whichdo not have an undesirable portion thereof corresponding to serial dataconverted from the forbidden codes are obtained.

Accordingly, when the method of transmitting data is applied toenciphered data transmission in which digital information data whichcorrespond to serial data obtained based on word sequence data whichcontain the digital information data in which forbidden codes includingtiming identification codes are contained and time reference code dataconstituted with timing identification codes, for example, such data asconstituting the HD-SDI signal, are subjected to enciphering process toproduce enciphered serial data and the enciphered serial data aretransmitted, the enciphered data transmission is carried out under thecondition wherein the enciphered serial data can be prevented fromcontaining an undesirable portion thereof corresponding to serial dataconverted from the forbidden codes.

Further, with the method of transmitting data, digital information datacontained in word sequence data which contain also time reference codedata constituted with timing identification codes in addition to thedigital information data are subjected to enciphering process in such amanner as not to produce forbidden code for producing enciphered digitalinformation data which do not contain any forbidden code, the enciphereddigital information data and the time reference code data aremultiplexed with each other to produce enciphered word sequence data tobe transmitted, and the enciphered digital information data obtainedfrom the enciphered word sequence data are subjected to decipheringprocess for reproducing the digital information data to be multiplexedwith the time reference code data to reproduce the word sequence data.Thereby, when the enciphered word sequence data to be transmitted areconverted into enciphered serial data, the enciphered serial data whichdo not have an undesirable portion thereof corresponding to serial dataconverted from the forbidden codes are obtained and the original serialdata are properly reproduced from the transmitted enciphered serial databy subjecting the transmitted enciphered serial data to the decipheringprocess.

Accordingly, when the method of transmitting data is applied toenciphered data transmission in which digital information data whichcorrespond to serial data obtained based on word sequence data whichcontain the digital information data in which forbidden codes includingtiming identification codes are contained and time reference code dataconstituted with timing identification codes, for example, such data asconstituting the HD-SDI signal, are subjected to enciphering process toproduce enciphered serial data to be transmitted, and the originalserial data are reproduced from the transmitted enciphered serial data,the enciphered data transmission is carried out under the conditionwherein the enciphered serial data can be prevented from containing anundesirable portion thereof corresponding to serial data converted fromthe forbidden codes and the original serial data can be surelyreproduced.

The invention claimed is:
 1. A method performed by apparatus fortransmitting video data, the method comprising the steps of: subjectingdigital information data to enciphering process in such a manner as notto produce forbidden code for producing enciphered digital informationdata which do not contain any forbidden code, wherein said digitalinformation data comprises a group of data including timingidentification data in the form of forbidden codes which are not used asinformation codes for representing information, wherein said digitalinformation data is contained in word sequence data which contain alsotime reference code data constituted with the timing identificationcodes in addition to the digital information data; producing encipheredword sequence data which include the enciphered digital information dataand the time reference code data; and transmitting the enciphered wordsequence data wherein the digital information data and one ofpseudo-random number data and genuine random number data are subjectedto operational process without producing forbidden code to produce theenciphered digital information data wherein the operational process towhich the digital information data and one of the pseudo-random numberdata and the genuine random number data are subjected without producingthe forbidden code, includes adding, subtracting and modulo operationsrelating to the digital information data and one of the pseudo-randomnumber data and the genuine random number data, the operational processbeing performed with data representing the number of the forbidden codesarranged out of one side of the range of the information codes of thedigital information data and data representing the number of theinformation codes of the digital information data, wherein the modulooperation obtains a remainder according to the number of the informationcodes of the digital information data, wherein, the adding, subtractingand modulo operations relating to the digital information data, isrepresented with an equation Ci={(Mi−N1)+Ei}mod N2+N1, wherein Mirepresents a code position number for each of the information codes ofthe digital information data, Ci represents a code position number foreach of the information codes of the enciphered digital informationdata, Ei represents code position number for each of 10-bit code of thepseudo-random number data, N1 represents the number of the forbiddencodes arranged out of one side of the range of the information codes ofthe digital information data, N2 represents the number of theinformation codes of the digital information data, and {(Mi−N1)+Ei}modN2 represents a remainder obtained by dividing {(Mi−N1)+Ei} by N2,wherein the forbidden codes exclude video data and wherein the videodata is in a high definition serial interface (HD-SDI) format.
 2. Amethod performed by apparatus for transmitting video data, the methodcomprising the steps of: subjecting digital information data toenciphering process in such a manner as not to produce forbidden codefor producing enciphered digital information data which do not containany forbidden code, wherein said digital information data comprises agroup of data including timing identification data in the form offorbidden codes which are not used as information codes for representinginformation, wherein said digital information data is contained in wordsequence data which contain also time reference code data constitutedwith the timing identification codes in addition to the digitalinformation data; producing enciphered word sequence data which includethe enciphered digital information data and the time reference codedata; and transmitting the enciphered word sequence data, wherein thedigital information data and one of pseudo-random number data andgenuine random number data are subjected to operational process withoutproducing forbidden code to produce the enciphered digital informationdata, wherein the operational process to which the digital informationdata and one of the pseudo-random number data and the genuine randomnumber data are subjected without producing the forbidden code, includesconverting operation for converting the digital information data toword-position-converted word sequence data having a range of informationcodes adjacent at its one end to the forbidden codes by writing thedigital information data in a memory and reading the digital informationdata from the memory, and adding, subtracting and modulo operationsrelating to the word-position-converted word sequence data and one ofthe pseudo-random number data and the genuine random number data, theoperational process being performed with data representing the number ofthe forbidden codes arranged out of one side of the range of theinformation codes of the word-position-converted word sequence data anddata representing the number of the information codes of theword-position-converted word sequence data, wherein the modulo operationobtains a remainder according to the number of the information codes ofthe digital information data, wherein, the adding, subtracting andmodulo operations relating to the digital information data, isrepresented with an equation Ci={(Mi−N1)+Ei}mod N2+N1, wherein Mirepresents a code position number for each of the information codes ofthe digital information data, Ci represents a code position number foreach of the information codes of the enciphered digital informationdata, Ei represents code position number for each of 10-bit code of thepseudo-random number data, N1 represents the number of the forbiddencodes arranged out of one side of the range of the information codes ofthe digital information data, N2 represents the number of theinformation codes of the digital information data, and {(Mi−N1)+Ei}modN2 represents a remainder obtained by dividing {(Mi−N1)+Ei} by N2,wherein the forbidden codes exclude video data, and wherein the videodata is in a high definition serial digital interface (HD-SDI) format.3. An apparatus for transmitting video data, the method comprising: anenciphering processor for subjecting digital information data toenciphering process in such a manner as not to produce forbidden codefor producing enciphered digital information data which do not containany forbidden code, wherein said digital information data comprises agroup of data including timing identification data in the form offorbidden codes which are not used as information codes for representinginformation, and wherein said digital information data is contained inword sequence data which contain also time reference code dataconstituted with the timing identification code in addition to thedigital information data; a data multiplexer for multiplexing theenciphered digital information data obtained from the encipheringprocessor and the time reference code data with each other to produceenciphered word sequence data; and a data transmitting portion fortransmitting the enciphered word sequence data obtained from the datamultiplexer, wherein the enciphering processor comprises a key datagenerating portion for supplying key data and an enciphering portion forsubjecting the digital information data and one of pseudo-random numberdata and genuine random number data to operational process withoutproducing forbidden code to produce the enciphered digital informationdata, wherein the enciphering portion comprises anadding-subtracting-modulo operation unit operative to perform adding,subtracting and modulo operations relating to the digital informationdata and one of the pseudo-random number data and the genuine randomnumber data with data representing the number of the forbidden codesarranged out of one side of the range of the information codes of thedigital information data and data representing the number of theinformation codes of the digital information data, as the operationalprocess to which the digital information data and one of thepseudo-random number data and the genuine random number data aresubjected without producing the forbidden code, wherein the modulooperation obtains a remainder according to the number of the informationcodes of the digital information data, wherein, the adding, subtractingand modulo operations relating to the digital information data, isrepresented with an equation Ci={(Mi−N1)+Ei}mod N2+N1, wherein Mirepresents a code position number for each of the information codes ofthe digital information data, Ci represents a code position number foreach of the information codes of the enciphered digital informationdata, Ei represents code position number for each of 10-bit code of thepseudo-random number data, N1 represents the number of the forbiddencodes arranged out of one side of the range of the information codes ofthe digital information data, N2 represents the number of theinformation codes of the digital information data, and {(Mi−N1)+Ei}modN2 represents a remainder obtained by dividing {(Mi−N1)+Ei} by N2,wherein the forbidden codes exclude video data and wherein the videodata is in a high definition serial digital interface (HD-SDI) format.4. An apparatus for transmitting video data, the method comprising: anenciphering processor for subjecting digital information data toenciphering process in such a manner as not to produce forbidden codefor producing enciphered digital information data which do not containany forbidden code, wherein said digital information data comprises agroup of data including timing identification data in the form offorbidden codes which are not used as information codes for representinginformation, and wherein said digital information data is contained inword sequence data which contain also time reference code dataconstituted with the timing identification code in addition to thedigital information data; a data multiplexer for multiplexing theenciphered digital information data obtained from the encipheringprocessor and the time reference code data with each other to produceenciphered word sequence data; and a data transmitting portion fortransmitting the enciphered word sequence data obtained from the datamultiplexer, wherein the enciphering processor comprises a key datagenerating portion for supplying key data and an enciphering portion forsubjecting the digital information data and one of pseudo-random numberdata and genuine random number data to operational process withoutproducing forbidden code to produce the enciphered digital informationdata, wherein the enciphering portion comprises a memory for convertingthe digital information data written therein to word-position-convertedword sequence data having a range of information codes adjacent at itsone end to the forbidden codes and read therefrom, and anadding-subtracting-modulo operation unit operative to perform adding,subtracting and modulo operations relating to theword-position-converted word sequence data and one of the pseudo-randomnumber data and the genuine random number data with data representingthe number of the forbidden codes arranged out of one side of the rangeof the information codes of the word-position-converted word sequencedata and data representing the number of the information codes of theword-position-converted word sequence data, as the operational processto which the digital information data and one of the pseudo-randomnumber data and the genuine random number data are subjected withoutproducing the forbidden code, wherein the modulo operation obtains aremainder according to the number of the information codes of thedigital information data, wherein, the adding, subtracting and modulooperations relating to the digital information data, is represented withan equation Ci={(Mi−N1)+Ei}mod N2+N1, wherein Mi represents a codeposition number for each of the information codes of the digitalinformation data, Ci represents a code position number for each of theinformation codes of the enciphered digital information data, Eirepresents code position number for each of 10-bit code of thepseudo-random number data, N1 represents the number of the forbiddencodes arranged out of one side of the range of the information codes ofthe digital information data, N2 represents the number of theinformation codes of the digital information data, and {(Mi−N1)+Ei}modN2 represents a remainder obtained by dividing {(Mi−N1)+Ei} by N2,wherein the forbidden codes exclude video data and wherein the videodata is in a high definition serial digital interface (HD-SDI) format.5. A method of an apparatus for transmitting video data, the methodcomprises the steps of: subjecting digital information data toenciphering process in such a manner as not to produce forbidden codefor producing enciphered digital information data which do not containany forbidden code, wherein said digital information data comprises agroup of data including timing identification data in the form offorbidden codes which are not used as information codes for representinginformation, and wherein said digital information data is contained inword sequence data which also contain time reference code dataconstituted with the timing identification codes in addition to thedigital information data; producing enciphered word sequence data whichinclude the enciphered digital information data and the time referencecode data; transmitting the enciphered word sequence data, receiving theenciphered word sequence data transmitted for obtaining the enciphereddigital information data from the enciphered word sequence data;subjecting the enciphered digital information data to decipheringprocess for reproducing the digital information data; and reproducingthe word sequence data which include the reproduced digital informationdata and the time reference code data wherein the digital informationdata and one of first pseudo-random number data and first genuine randomnumber data are subjected to operational process without producingforbidden code to produce the enciphered digital information data andthe enciphered digital information data and one of second pseudo-randomnumber data and second genuine random number data are subjected tooperational process to produce the reproduced digital information data,wherein the operational process to which the digital information dataand one of the first pseudo-random number data and the first genuinerandom number data are subjected without producing the forbidden code,includes adding, subtracting and modulo operations relating to thedigital information data and one of the first pseudo-random number dataand the first genuine random number data, the operational process beingperformed with data representing the number of the forbidden codesarranged out of one side of the range of the information codes of thedigital information data and data representing the number of theinformation codes of the digital information data, and the operationalprocess to which the enciphered digital information data and one of thesecond pseudo-random number data and the second genuine random numberdata are subjected, includes adding, subtracting and modulo operationsrelating to the enciphered digital information data and one of thesecond pseudo-random number data and the second genuine random numberdata, the operational process being performed with data representing thenumber of the forbidden codes arranged out of one side of the range ofthe information codes of the enciphered digital information data anddata representing the number of the information codes of the enciphereddigital information data, wherein the modulo operation obtains aremainder according to the number of the information codes of thedigital information data, wherein, the adding, subtracting and modulooperations relating to the digital information data, is represented withan equation Ci={(Mi−N1)+Ei}mod N2+N1, wherein Mi represents a codeposition number for each of the information codes of the digitalinformation data, Ci represents a code position number for each of theinformation codes of the enciphered digital information data, Eirepresents code position number for each of 10-bit code of thepseudo-random number data, N1 represents the number of the forbiddencodes arranged out of one side of the range of the information codes ofthe digital information data, N2 represents the number of theinformation codes of the digital information data, and {(Mi−N1)+Ei}modN2 represents a remainder obtained by dividing {(Mi−N1)+Ei} by N2,wherein the forbidden codes exclude video data and wherein the videodata is in a high definition serial digital interface (HD-SDI) format.6. A method of an apparatus for transmitting video data, the methodcomprises the steps of: subjecting digital information data toenciphering process in such a manner as not to produce forbidden codefor producing enciphered digital information data which do not containany forbidden code, wherein said digital information data comprises agroup of data including timing identification data in the form offorbidden codes which are not used as information codes for representinginformation, and wherein said digital information data is contained inword sequence data which also contain time reference code dataconstituted with the timing identification codes in addition to thedigital information data; producing enciphered word sequence data whichinclude the enciphered digital information data and the time referencecode data; transmitting the enciphered word sequence data, receiving theenciphered word sequence data transmitted for obtaining the enciphereddigital information data from the enciphered word sequence data;subjecting the enciphered digital information data to decipheringprocess for reproducing the digital information data; and reproducingthe word sequence data which include the reproduced digital informationdata and the time reference code data wherein the digital informationdata and one of first pseudo-random number data and first genuine randomnumber data are subjected to operational process without producingforbidden code to produce the enciphered digital information data andthe enciphered digital information data and one of second pseudo-randomnumber data and second genuine random number data are subjected tooperational process to produce the reproduced digital information data,wherein the operational process to which the digital information dataand one of the first pseudo-random number data and the first genuinerandom number data are subjected without producing the forbidden code,includes converting operation for converting the digital informationdata to word-position-converted word sequence data having a range ofinformation codes adjacent at its one end to the forbidden codes bywriting the digital information data in a first memory and reading thedigital information data from the first memory, and adding, subtractingand modulo operations relating to the word-position-converted wordsequence data and one of the first pseudo-random number data and thefirst genuine random number data, the operational process beingperformed with data representing the number of the forbidden codesarranged out of one side of the range of the information codes of theword-position-converted word sequence data and data representing thenumber of the information codes of the word-position-converted wordsequence data, and the operational process to which the enciphereddigital information data and one of the second pseudo-random number dataand the second genuine random number data are subjected, includesadding, subtracting and modulo operations relating to the enciphereddigital information data and one of the second pseudo-random number dataand the second genuine random number data, the operational process beingperformed with data representing the number of the forbidden codesarranged out of one side of the range of the information codes of theenciphered digital information data and data representing the number ofthe information codes of the enciphered digital information data, andconverting operation for converting word-position-converted wordsequence data obtained by the adding, subtracting and modulo operationsrelating to the enciphered digital information data and written in asecond memory to the reproduced digital information data read from thesecond memory, wherein the modulo operation obtains a remainderaccording to the number of the information codes of the digitalinformation data, wherein, the adding, subtracting and modulo operationsrelating to the digital information data, is represented with anequation Ci={(Mi−N1)+Ei}mod N2+N1, wherein Mi represents a code positionnumber for each of the information codes of the digital informationdata, Ci represents a code position number for each of the informationcodes of the enciphered digital information data, Ei represents codeposition number for each of 10-bit code of the pseudo-random numberdata, N1 represents the number of the forbidden codes arranged out ofone side of the range of the information codes of the digitalinformation data, N2 represents the number of the information codes ofthe digital information data, and {(Mi−N1)+Ei}mod N2 represents aremainder obtained by dividing {(Mi−N1)+Ei} by N2, wherein the forbiddencodes exclude video data and wherein the video data is in a highdefinition serial digital interface (HD-SDI) format.
 7. An apparatus fortransmitting video data, the method comprising: an enciphering processorfor subjecting digital information data to enciphering process in such amanner as not to produce forbidden code for producing enciphered digitalinformation data which do not contain any forbidden code, wherein saiddigital information data containing a group of data including timingidentification data in the form of forbidden codes which are not used asinformation codes for representing information, and wherein said digitalinformation data is contained in word sequence data which also containtime reference code data constituted with the timing identification codein addition to the digital information data, a first data multiplexerfor multiplexing the enciphered digital information data obtained fromthe enciphering processor and the time reference code data with eachother to produce enciphered word sequence data; a data transmittingportion for transmitting the enciphered word sequence data obtained fromthe first data multiplexer; a deciphering processor for receiving theenciphered word sequence data transmitted by the data transmittingportion to obtain the enciphered digital information data from theenciphered word sequence data and subjecting the enciphered digitalinformation data to deciphering process for reproducing the digitalinformation data; and a second data multiplexer for multiplexing thereproduced digital information data and the time reference code datawith each other to reproduce the word sequence data, wherein theenciphering processor comprises a first key data generating portion forsupplying first key data and an enciphering portion for subjecting thedigital information data and one of first pseudo-random number data andfirst genuine random number data to operational process withoutproducing forbidden code to produce the enciphered digital informationdata, and the deciphering processor comprises a second key datagenerating portion for supplying second key data and an decipheringportion for subjecting the enciphered digital information data and oneof second pseudo-random number data and second genuine random numberdata to operational process to obtain the reproduced digital informationdata, wherein the enciphering portion comprises a firstadding-subtracting-modulo operation unit operative to perform adding,subtracting and modulo operations relating to the digital informationdata and one of the first pseudo-random number data and the firstgenuine random number data with data representing the number of theforbidden codes arranged out of one side of the range of the informationcodes of the digital information data and data representing the numberof the information codes of the digital information data, as theoperational process to which the digital information data and one of thefirst pseudo-random number data and the first genuine random number dataare subjected without producing the forbidden code, and the decipheringportion comprises a second adding-subtracting-modulo operation unitoperative to perform adding, subtracting and modulo operations relatingto the enciphered digital information data and one of the secondpseudo-random number data and the second genuine random number data withdata representing the number of the forbidden codes arranged out of oneside of the range of the information codes of the enciphered digitalinformation data and data representing the number of the informationcodes of the enciphered digital information data, as the operationalprocess to which the enciphered digital information data and one of thesecond pseudo-random number data and the second genuine random numberdata are subjected, wherein the modulo operation obtains a remainderaccording to the number of the information codes of the digitalinformation data, wherein, the adding, subtracting and modulo operationsrelating to the digital information data, is represented with anequation Ci={(Mi−N1)+Ei}mod N2+N1, wherein Mi represents a code positionnumber for each of the information codes of the digital informationdata, Ci represents a code position number for each of the informationcodes of the enciphered digital information data, Ei represents codeposition number for each of 10-bit code of the pseudo-random numberdata, N1 represents the number of the forbidden codes arranged out ofone side of the range of the information codes of the digitalinformation data, N2 represents the number of the information codes ofthe digital information data, and {(Mi−N1)+Ei}mod N2 represents aremainder obtained by dividing {(Mi−N1)+Ei} by N2, wherein the forbiddencodes exclude video data and wherein the video data is in a highdefinition serial digital interface (HD-SDI) format.
 8. An apparatus fortransmitting video data, the method comprising: an enciphering processorfor subjecting digital information data to enciphering process in such amanner as not to produce forbidden code for producing enciphered digitalinformation data which do not contain any forbidden code, wherein saiddigital information data containing a group of data including timingidentification data in the form of forbidden codes which are not used asinformation codes for representing information, and wherein said digitalinformation data is contained in word sequence data which also containtime reference code data constituted with the timing identification codein addition to the digital information data, a first data multiplexerfor multiplexing the enciphered digital information data obtained fromthe enciphering processor and the time reference code data with eachother to produce enciphered word sequence data; a data transmittingportion for transmitting the enciphered word sequence data obtained fromthe first data multiplexer; a deciphering processor for receiving theenciphered word sequence data transmitted by the data transmittingportion to obtain the enciphered digital information data from theenciphered word sequence data and subjecting the enciphered digitalinformation data to deciphering process for reproducing the digitalinformation data; and a second data multiplexer for multiplexing thereproduced digital information data and the time reference code datawith each other to reproduce the word sequence data, wherein theenciphering processor comprises a first key data generating portion forsupplying first key data and an enciphering portion for subjecting thedigital information data and one of first pseudo-random number data andfirst genuine random number data to operational process withoutproducing forbidden code to produce the enciphered digital informationdata, and the deciphering processor comprises a second key datagenerating portion for supplying second key data and an decipheringportion for subjecting the enciphered digital information data and oneof second pseudo-random number data and second genuine random numberdata to operational process to obtain the reproduced digital informationdata, wherein the enciphering portion comprises a first memory forconverting the digital information data written therein toword-position-converted word sequence data having a range of informationcodes adjacent at its one end to the forbidden codes and read therefrom,and a first adding-subtracting-modulo operation unit operative toperform adding, subtracting and modulo operations relating to theword-position-converted word sequence data and one of the firstpseudo-random number data and the first genuine random number data withdata representing the number of the forbidden codes arranged out of oneside of the range of the information codes of theword-position-converted word sequence data and data representing thenumber of the information codes of the word-position-converted wordsequence data, as the operational process to which the digitalinformation data and one of the first pseudo-random number data and thefirst genuine random number data are subjected without producing theforbidden code, and the deciphering portion comprises a secondadding-subtracting-modulo operation unit operative to perform adding,subtracting and modulo operations relating to the enciphered digitalinformation data and one of the second pseudo-random number data and thesecond genuine random number data with data representing the number ofthe forbidden codes arranged out of one side of the range of theinformation codes of the enciphered digital information data and datarepresenting the number of the information codes of the enciphereddigital information data, as the operational process to which theenciphered digital information data and one of the second pseudo-randomnumber data and the second genuine random number data are subjected, anda second memory for converting word-position-converted word sequencedata obtained from the second adding-subtracting-modulo operation unitand written therein to the reproduced digital information data readtherefrom, wherein the modulo operation obtains a remainder according tothe number of the information codes of the digital information data,wherein, the adding, subtracting and modulo operations relating to thedigital information data, is represented with an equationCi={(Mi−N1)+Ei}mod N2+N1, wherein Mi represents a code position numberfor each of the information codes of the digital information data, Cirepresents a code position number for each of the information codes ofthe enciphered digital information data, Ei represents code positionnumber for each of 10-bit code of the pseudo-random number data, N1represents the number of the forbidden codes arranged out of one side ofthe range of the information codes of the digital information data, N2represents the number of the information codes of the digitalinformation data, and {(Mi−N1)+Ei}mod N2 represents a remainder obtainedby dividing {(Mi−N1)+Ei} by N2, wherein the forbidden codes excludevideo data and wherein the video data is in a high definition serialdigital interface (HD-SDI) format.
 9. A method of an apparatus forreceiving video data, the method comprising the steps of: receivingenciphered word sequence data, wherein the enciphered word sequence dataincludes enciphered digital information data and time reference codedata, wherein enciphered digital information data and one ofpseudo-random number data and genuine random number data are subjectedto operational process to produce digital information data, wherein theoperational process to which the enciphered digital information data andone of the pseudo-random number data and the genuine random number dataare subjected, includes adding, subtracting and modulo operationsrelating to the enciphered digital information data and one of thepseudo-random number data and the genuine random number data, theoperational process being performed with data representing the number ofthe forbidden codes arranged out of one side of the range of theinformation codes of the enciphered digital information data and datarepresenting the number of the information codes of the digitalinformation data, wherein said digital information data comprises agroup of data including timing identification data in the form offorbidden codes which are not used as information codes for representinginformation, wherein the modulo operation obtains a remainder accordingto the number of the information codes of the digital information data,wherein, the adding, subtracting and modulo operations relating to thedigital information data, is represented with an equationCi={(Mi−N1)+Ei}mod N2+N1, wherein Mi represents a code position numberfor each of the information codes of the digital information data, Cirepresents a code position number for each of the information codes ofthe enciphered digital information data, Ei represents code positionnumber for each of 10-bit code of the pseudo-random number data, N1represents the number of the forbidden codes arranged out of one side ofthe range of the information codes of the digital information data, N2represents the number of the information codes of the digitalinformation data, and {(Mi−N1)+Ei}mod N2 represents a remainder obtainedby dividing {(Mi−N1)+Ei} by N2, wherein the forbidden codes excludevideo data and wherein the video data is in a serial transmission highdefinition signal (HD-SDI) format.
 10. A method of an apparatus forreceiving video data, the method comprising the steps of: receivingenciphered word sequence data, wherein the enciphered word sequence dataincludes enciphered digital information data and time reference codedata, wherein enciphered digital information data and one ofpseudo-random number data and genuine random number data are subjectedto an operational process to produce digital information data, whereinthe operational process to which the enciphered digital information dataand one of the pseudo-random number data and the genuine random numberdata are subjected, includes adding, subtracting and modulo operationsrelating to the enciphered digital information data and one of thepseudo-random number data and the genuine random number data, theoperational process being performed with data representing the number ofthe forbidden codes arranged out of one side of the range of theinformation codes of the enciphered digital information data and datarepresenting the number of the information codes of the enciphereddigital information data, and converting operation for convertingword-position-converted word sequence data obtained by the adding,subtracting and modulo operations relating to the enciphered digitalinformation data and written in a memory to the digital information dataread from the memory, wherein said digital information data comprises agroup of data including timing identification data in the form offorbidden codes which are not used as information codes for representinginformation, wherein the modulo operation obtains a remainder accordingto the number of the information codes of the digital information data,wherein, the adding, subtracting and modulo operations relating to thedigital information data, is represented with an equationCi={(Mi−N1)+Ei}mod N2+N1, wherein Mi represents a code position numberfor each of the information codes of the digital information data, Cirepresents a code position number for each of the information codes ofthe enciphered digital information data, Ei represents code positionnumber for each of 10-bit code of the pseudo-random number data, N1represents the number of the forbidden codes arranged out of one side ofthe range of the information codes of the digital information data, N2represents the number of the information codes of the digitalinformation data, and {(Mi−N1)+Ei}mod N2 represents a remainder obtainedby dividing {(Mi−N1)+Ei} by N2, wherein the forbidden codes excludevideo data and wherein the video data is in a high definition serialdigital interface (HD-SDI) format.